UPDATE 9:20 a.m. EDT: Most of  the senior Taliban prisoners released by the insurgent forces have been relocated to Afghanistan's capital of Kabul, the New York Times reported. A local official estimated to the outlet that some 70 percent of the province was under Taliban control.

Original story: 

Hundreds of Taliban fighters took control of several areas in Kunduz, Afghanistan, during a surprise attack Monday, BBC reported. The northern city is of strategic importance and was a former stronghold of the Taliban before the militant group was overthrown in 2001.

Intense fighting broke out across the city Monday, as the assault came from several directions, with causalities on both sides. At least eight people, some of which were police officers, have been killed, with 50 others wounded, reported Al Jazeera. Kunduz has been put on lockdown as security forces attempted to fight back, the news outlet added.

The Taliban reportedly took control of a number of government offices in the coordinated attacks. About half of the city had been captured by the Taliban in the offensive, Sayed Sarwar Hussaini, spokesman for the provincial police chief of Kunduz, told the Associated Press. Twenty Taliban fighters had been killed with three police officers wounded, he also said, according to Reuters. 

"We have enough forces and will drive them out soon," Hussaini said to Reuters.

The Taliban have seized control of Kunduz's city prison, releasing all prisoners, as well as a United Nations office, TOLONews in Afghanistan tweeted. Recent reports have suggested that fighting in the city is ongoing. Afghan military helicopters fired at insurgents in a number of areas outside the city center in the afternoon with special forces from outside the region on the way, Reuters reported.

Government officials also told BBC that reinforcements have been sent to Kunduz. The city, a provincial capital, is a connecting point for major roads that link central and northern Afghanistan. It also supplies half of Afghanistan's rice crop, according to BBC. Kunduz has seen an uptick in attacks in recent months, with the Taliban joining other insurgents.

The Taliban's spokesman sent a warning to the people living in Kunduz.

"The mujahideen are trying to avoid any harm to Kunduz residents," Zabihullah Majahid posted to Twitter, according to Reuters. "Residents have to be assured they will not face any problem from our side." 

The Taliban also reportedly briefly seized control of a hospital, quickly leaving after not finding wounded government soldiers. Afghanistan's police, trained by NATO, have been fighting Taliban militants this year without the help of foreign forces that ended their combat mission in December last year.