UPDATE: Friday, 7:30 P.M. EST —  According to a press statement released Friday, the U.S. Embassy in Kampala is advising U.S. citizens in the capital "to stay off the streets for the remainder of the day, due to reports of police and military clearing the streets. We also advise U.S. citizens to continue to monitor local media."

CORRECTION: Friday, 7:20 P.M. EST — This story has been changed to delete a reference to an alleged statement from U.S. State Department officials about evacuating Americans from Uganda. The statement had been doctored and was false, a U.S. State Department spokesperson told International Business Times on Friday night. 

UPDATE: Friday, 1:55 p.m. EST — Uganda's main opposition candidate and presidential challenger Kizza Besigye has been released from police custody in the capital of Kampala, a police spokesman said Friday. Besigye was detained hours earlier at his political party's headquarters in Kampala for allegedly trying to announce final election results. His release comes not long after U.S. Secretary of State John Kerry spoke with Ugandan President Yoweri Museveni over the telephone to express concern over Besigye's arrest.

UPDATE: Friday, 1:26 p.m. EST — U.S. Secretary of State John Kerry spoke with Ugandan President Yoweri Museveni over the telephone Friday "to underscore that Uganda's progress depends on adherence to democratic principle in the ongoing election process." Kerry also "expressed  his concern" about the detention of presidential challenger Kizza Besigye and the harassment of opposition party members, the U.S. Department said in a statement.

Kerry urged Museveni, who is seeking to extend his 30-year grip on power, to "rein in" security forces and end the blockage of several popular social media and mobile money sites starting on Election Day. His comments come hours after Ugandan police arrested Besigye and raided the headquarters of his political party Forum for Democratic Change (FDC) in the capital of Kampala on Friday, as dozens of polling stations around the country were forced to reopen for a second day of voting.

UPDATE: Friday, 11:30 a.m. EST — Ugandan police said Friday main opposition candidate Kizza Besigye was "stopped from announcing purportedly final results" of the country's presidential election. Besigye's political party, Forum for Democratic Change (FDC), tweeted earlier Friday that he had been arrested during a police raid at their headquarters in the capital of Kampala.

"It has been made clear through various forums that any attempt by anyone other than the Electoral Commission, including the FDC party, to declare their own results will amount to disturbing public order," Patrick Onyango, spokesman for Kampala Metropolitan Police, said in a statement, which was posted on social media. "Whereas we appreciate that many people are anxious about the results of the elections, we call upon all peace-loving Ugandans to exercise restraint, good judgement and a sense of decorum in handling matters to do with election results."

Onyango noted that Uganda's constitution grants the power of declaring these results to the country's electoral commission. The statement did not say whether Besigye, who is running against incumbent Yoweri Museveni of the ruling National Resistance Movement, remains in police custody.

UPDATE: Friday, 10:48 a.m. EST — Partial election results from Uganda's main opposition party Forum for Democratic Change (FDC) show its candidate Kizza Besigye is narrowly beating incumbent Yoweri Museveni in the contentious presidential race. Out of the 300,331 votes counted so far, Besigye has garnered 51.9 percent while Museveni is not far behind with 44.6 percent, according to data collected by FDC officials from 115 polling stations across the country.

However, provisial results from Uganda's electoral commission maintain Museveni in the lead with 62.82 percent of votes from 44.5 percent -- or 12,465 -- of the nation's polling stations. Meanwhile, Besigye has 32.72 percent of the ballots tallied thus far and former Ugandan prime minister Amama Mbabazi has just 1.71 percent. The remaining five candidates have less than 1 percent.

UPDATE: Friday, 9:33 a.m. EST — Despite media reports that presidential challenger Kizza Besigye was released, the head of a global relief organization said he remains in police custody in the town of Nagalama, some 22 miles outside Uganda's capital. Winnie Byanyima, executive director of Oxfam International, said she spoke with Besigye and he believes police arrested him to stop his political party from holding a press conference on Friday.

"It's not true that [Besigye] was brought home by police. He [and his] colleagues are held at Nagalama police [station]," Byanyima, who is Ugandan-born, tweeted Friday. "I've spoken [with Besigye]."

Besigye, who is vying for Uganda's presidency against incumbent Yoweri Museveni, was detained earlier Friday during a police raid on the headquarters of his Forum for Democratic Change party. This is the third time in the span of a week that he has been arrested.

Ugandan police have not yet commented on the reason for his arrest. International Business Times has contacted Uganda Police Force, but a spokesperson did not immediately return requests for comment.

UPDATE: Friday, 9:05 a.m. EST — Uganda's local currency was steady Friday amid subdued economic activity as fears of post-election violence and chaos loom. The shilling remained unchanged from Wednesday's market close at 3,420/3,430, which was weaker than Monday's close of 3,410/3,420, according to Reuters.

The markets were closed Thursday as the East African nation held a controversial presidential election, in which President Yoweri Museveni is seeking to extend his 30-year rule. In the days leading up to the vote, a number of businesses in the capital of Kampala and other areas temporarily closed their doors and have remained shuttered.

"Most businesses are still closed because of the uncertainty surrounding the election so demand is virtually dead both from banks and our corporate clients," a trader from a leading commercial bank told Reuters on Friday.

At least one person was killed Tuesday as riot police clashed with opposition supporters at a rally in Kampala, after briefly detaining presidential challenger Kizza Besigye. Violence did not disrupt Thursday's vote, but Besigye, along with some of his supporters, was arrested again and later released. Also, the late delivery of ballot boxes and voting papers to dozens of polling stations prevented many Ugandans from casting their vote. A total of 36 polling stations in Kampala and the surrounding Wakiso district were slated to reopen Friday morning for a second day of voting.

UPDATE: Friday, 7:57 a.m. EST — Preliminary results from Uganda's electoral commission show incumbent Yoweri Museveni of the ruling National Resistance Movement is leading the presidential race with 61.45 percent of votes tallied, with main opposition candidate Kizza Besigye of the Forum for Democratic Change trailing with 34.57 percent. Former Ugandan Prime Minister Amama Mbabazi, who is running under the Go Forward banner after failing to win the ruling party's nomination, is in a distant third place with 1.21 percent, while the remaining five candidates each have less than 1 percent.

So far, the Uganda Electoral Commission has counted votes from just 24.27 percent of the thousands of polling stations across the country. Besigye's party has been conducting its own tally of votes and posting the alternative preliminary results on social media. Forum for Democratic Change spokesman Ssemujju Nganda tweeted around 1 a.m. EST that Besigye was allegedly ahead of Museveni 50 percent to 46 percent, after counting ballots from 673 polling stations.

Dozens of polling stations were forced to open for a second day of voting Friday after the late delivery of polling materials prevented many Ugandans from casting their ballots. A total of 36 polling stations in the capital of Kampala and the surrounding Wakiso district were slated to reopen Friday morning. Voting took place smoothly in some 28,000 other polling stations around the country, according to Agence France-Presse news agency.

UPDATE: Friday, 7:31 a.m. EST — Uganda's main opposition candidate Kizza Besigye was arrested again Friday, one day after the East African country held controversial elections. The presidential hopeful, who is running against incumbent Yoweri Museveni, was detained during a police raid on his political party's headquarters in the capital of Kampala. He was also arrested briefly Thursday before being released.

Besigye's party, the Forum for Democratic Change (FDC), tweeted that its offices in Najjanankumbi in the capital were "under attack" by Ugandan security forces. The main opposition party has been conducting its own tally of ballots and announcing alternative results via social media. The FDC said Besigye and several of his supporters were taken into police custody.

"They have brought more weapons and are spraying teargas [sic] through our windows," the main opposition party posted on its official Twitter account. "We need help from the international community. The situation is getting out of hand here at our FDC headquarters."

This is the third time in the span of a week that Besigye has been apprehended Besigye. Ugandan police have not yet commented on the reason for his arrest, according to BBC News. International Business Times has contacted Uganda Police Force, but a spokesperson did not immediately return requests for comment.

UPDATE: Thursday, 3:25 p.m. EST — Ugandan police released a statement explaining why opposition candidate Kizza Besigye was arrested earlier Thursday, during the country's presidential election. The statement, which was posted on social media by journalists, said Besigye was "apprehended for criminal trespass and assault and later released on police bond."

According to the statement, Besigye arrived at one of Uganda Police Force's security facilities in an an area of the capital of Kampala with "a team of journalists with cameras and a rowdy crouwd." The opposition figure, along with Kampala Lord Mayor Elias Lukwago, then "stormed" the premises and "assaulted a police officer," causing "grievous harm to him."

"This was under a false allegation that the Uganda Police Force was rigging and tallying votes in favor of the National Resistance Movement (ruling) party at the Naguru-based installation. The logic here does not add up by any reason," the police statement said. 

Besigye's opposition party Forum for Democratic Change claimed to have discovered the site of a ballot rigging center at a house in Kampala. The presidential hopeful demanded to search the building but was swiftly taken into police custody and removed from the scene, a Forum for Democratic Change spokesman said earlier Thursday.

Besigye is one of seven opposition candidates against longtime incumbent Yoweri Museveni of the National Resistance Movement. He has been repeatedly detained by Ugandan police in the past and released without charges hours later.

UPDATE: Thursday, 2:43 p.m. EST — Ugandan President Yoweri Museveni, who is seeking a fifth term in office, warned that no one is authorized to announce the results  of Thursday's presidential and parliamentary elections except the country's official electoral commission. The longtime leader, who has ruled Uganda for three decades, also urged citizens to remain calm as they await the poll results, according to Uganda's government-owned New Vision newspaper.

“Nobody has got power to announce the elections results. If one does, that person will be arrested and prosecuted in accordance with the law,” Museveni told journalists Thursday, after he voted at Kaaro High School in Kenshunga sub-county in Uganda's western Kiruhuura district. The incumbent, who is running against seven other candidates, arrived at the polling station in the afternoon and apparently waited in line with other registered voters to cast his ballot.

UPDATE: Thursday, 1:15 p.m. EST — International election observer and former Nigerian President Olusegun Obasanjo warned Thursday that the hours-long delays in delivering voting materials to various polling centers during Uganda's general elections would not "inspire trust" in the electoral process, according to pan-African media site Africanews.

“A delay of an hour or two is excusable. Delays of three, four, five and even six hours, especially in Kampala, are absolutely inexcusable and will not inspire trust and confidence in the system and the process,” said Obasanjo, who is leading a 13-member team from the Commonwealth Observer Group, which monitors elections in various countries around the world.

UPDATE: Thursday, 12:43 p.m. EST — Kizza Besigye, the leading opposition candidate in Uganda's presidential election, was been released from police custody Thursday hours after he was briefly arrested in the capital of Kampala during Thursday's general elections, a VOA News journalist reported.

There are numerous reports that Kampala Lord Mayor Elias Lukwago was also briefly detained and released along with Besigye. In an interview with a government-owned daily newspaper, however, Ugandan police denied that Besigye was arrested following his confrontation with officers outside a house the opposition claims is the site of ballot rigging operations.

“We only escorted him to his home. A civilian cannot just invade a security facility,” Ugandan police spokesman Fred Enanga told New Vision newspaper.

Recent surveys indicate it'll be a tight race between Besigye and incumbent Yoweri Museveni. An opinion poll conducted between Feb. 1-8 by Ipsos, a Paris-based global market research firm, shows Besigye trailing Museveni by 28 percent to 53 percent, with a margin of error of plus or minus 2.2 percentage points. Another poll conducted between Dec. 19 and Jan. 10 by Research World International, a Kampala-based research agency, showed that 51 percent of likely voters support Museveni, 32 percent support Besigye and 12 percent would vote for another presidential candidate, Amama Mbabazi.

Besigye is running in his fourth presidential election on behalf of Uganda’s main opposition party, Forum for Democratic Change. The longtime opposition figure is a trained physician and a former military officer who parted ways with Museveni 15 years ago, calling him a dictator.

UPDATE: Thursday, 11:48 a.m. EST — A spokesman for Uganda's main opposition party Forum for Democratic Change confirmed to BBC News that the group's presidential candidate, Kizza Besigye, was indeed arrested by police during the country's general elections Thursday. The spokesman said Besigye and other party members demanded to search a house, which the opposition claims is the site of a ballot rigging center. The presidential hopeful was then taken into custody and removed from the scene in a police vehicle.

It's not the first time Besigye has been arrested. The longtime opposition figure was briefly detained Monday amid clashes between his supporters and riot police. One person was killed and 19 others wounded, according to Reuters.

UPDATE: Thursday, 10:40 a.m. EST — Kizza Besigye, an opposition candidate running in Uganda's presidential election, was arrested Thursday, an Al Jazeera journalist reported on social media. The presidential hopeful was apparently taken into police custody after he demanded access to a house in the capital Kampala, where he claims vote rigging operations have been taking place.

UPDATE: Thursday, 10:26 a.m. EST — Opposition candidate Kizza Besigye said his presidential campaign team has allegedly discovered a ballot rigging center inside a house in Uganda's capital of Kampala. The occupants tried to escape out the back when Besigye and his team demanded access to the building, but they were apparently stopped and found carrying police guns, an Al Jazeera journalist reported.

Original story:

Uganda's electoral commission has extended the voting deadline at polling stations around the East African nation from 4 p.m. to 7 p.m. local time during Thursday's presidential and parliamentary elections, according to Kenyan newspaper Daily Nation. The announcement comes after police fired tear gas to disperse a crowd of angry voters in Kampala who were reacting to ballot boxes and papers arriving hours late in some polling stations in the capital city and surrounding Wakiso district.

In some areas, polls remained closed five hours after voting was scheduled to start, at 7 a.m. local time. At one polling center in Kampala, hundreds of voters shouted and gestured their frustration at election officials, according to Agence France-Presse. Uganda’s electoral commission has apologized for the delayed deliveries of voting materials to various areas, UPI reported.

Ugandans were further frustrated when they realized the government had shut down internet services and mobile money transfers in the East African country during Thursday's elections, citing security concerns. Godfrey Mutabazi, the head of Uganda Communications Commission, confirmed to local television station NTV Uganda that it had temporarily blocked social media, including Facebook, Twitter, Instagram and WhatsApp, following complaints from the country’s electoral commission that the platforms were being used by candidates to bribe voters and to campaign past Tuesday’s campaigning deadline. But some voters and journalists in the country bypassed the temporary ban by using a virtual person network, or VPN, to log on to social networks.

Despite the chaos and confusion, voters waited for hours in long lines under the hot sun to cast their ballots at polling stations around the country. The presidential race, which has been deemed Uganda’s most competitive ever, pits incumbent Yoweri Museveni against seven opposition candidates, including his former Vice President Amama  Mbabazi as well as his former military officer and physician Kizza Besigye. After three decades in power, Museveni is seeking a controversial fifth term in office, years after he won a campaign to abolish presidential term limits in the constitution.

This is a developing story.

CORRECTION: A tweet that was included in an earlier version of this story was removed after discovering it was sent from a parody account. The story has been updated to reflect this correction.