[Update 7:59 p.m. ET: This article includes new information from the explosions in Kabul, Afghanistan]

Two explosions accompanied by gunfire hit Afghanistan’s capital Kabul on Thursday, only hours after the U.S. and allies issued a warning about a terrorist attack. The New York Times reported that 13 U.S. service members and at least 60 Afghan civilians were killed. Fifteen more Americans were wounded while at least 140 Afghans were wounded.

In a tweet, U.S. Department of Defense spokesman John Kirby confirmed that an explosion took place at the Kabul airport’s Abbey Gate. Kirby later confirmed on Twitter that the explosion at the Abbey Gate "was the result of a complex attack that resulted in a number of US and civilian casualties" and that a second explosion took place near the Baron Hotel nearby.

Secretary of Defense Lloyd Austin released his own statement in response to the loss of U.S. troops in which he expressed his condolences to the families of those killed and wounded. Austin said the U.S. military would not be dissuaded from completing its mission because "to do anything less -- especially now -- would dishonor the purpose and sacrifice these men and women have rendered our country and the people of Afghanistan."

Gen. Kenneth McKenzie, the U.S. commander for Central Command which oversees operations in Afghanistan, told the Pentagon press pool that the Islamic State (ISIS) was responsible for the "cowardly attack" on Kabul's airport. In his briefing, McKenzie praised the work of U.S. service members and offered his assurances that ISIS will not stop the completion of the evacuation mission.

The CENTCOM commander confirmed the number of U.S. casualties, but said further investigation was needed to determine how it occured. He insisted that the number of troops on the ground now was sufficient to complete the mission ahead of the U.S. scheduled evacuation deadline of Aug. 31. He also added that commanders on the groun would coordinate with the Taliban to expand a wider security perimeter near the airport to prevent more attacks.

According to local Afghan news agency TOLOnews, eyewitnesses say that an explosion came from inside a crowd of citizens near the airport. A local reporter for the outlet added that no exact casualty number is available, but several wounded have been taken to a hospital. Emergency, an Italian non-government organization on the ground in Afghanistan, said about 60 people were brought to its surgical center after the blasts.

President Joe Biden was briefed on the attack and postponed a scheduled press conference with Israel's Prime Minister Naftali Bennett. Vice President Kamala Harris also received a briefing, CNN reported. France’s ambassador in Kabul urged French citizens to avoid the airport, following in the steps of the U.S. and other countries. French President Emmanuel Macron announced that the ambassador would be moved from Kabul to Paris as a result of the deteriorating security conditions at the airport. British Prime Minister Boris Johnson convened an emergency meeting of his cabinet in response to the Kabul attack.

"To those who carried out this attack we will not forgive. We will not forget. We will hunt you down and make you pay. We will continue the evacuation," Biden said in a late afternoon address to the nation. "We will respond with force and precision. These ISIS terrorists will not win. We will complete our mission."

Biden asked for a moment of silence and took questions from the media.

"We have some reason to believe we know who they are and we will find ways of our choosing to get them wherever they are," he said. "There is no evidence that I have been given that there has been collusion between the Taliban and ISIS.

"I know of no conflict where when a war was ending, one side was able to guarantee that everyone who wanted to be extracted from a country would get out. I would argue that millions of Afghan citizens ... who, if given a chance, they would be onboard a plane tomorrow. Getting every single person out can't be guaranteed by anybody. I bear responsibility for fundamentally all that's happened."

The Taliban condemned the bombing but appeared to blame the U.S. for allowing the attack to take place in a statement shared over Twitter by its spokesperson.

"The Islamic Emirate strongly condemns the bombing of civilians at Kabul airport, which took place in an area where U.S. forces are responsible for security," Zabihullah Mujahid wrote on Twitter.

"The Islamic Emirate is paying close attention to the security and protection of its people, and evil circles will be strictly stopped," he continued.

Kabul’s Hamid Karzai International Airport is the site of an ongoing evacuation of Americans, Afghans and others that began after the Taliban took control of the capital on Aug. 15. The airport is also hosting thousands of Afghans, who are hoping to escape what they fear will be a harsh life under Taliban rule.

Early Thursday morning, the U.S. embassy in Kabul issued a “high threat” warning and urged Americans in the city to avoid traveling to the airport at this time. Officials from the U.K., Australia and New Zealand issued similar warnings to their citizens.

ISIS later claimed responsibility for the attack against the airport through its Amaq News Agency, but the specific affiliate likely to have conducted the attack was ISIS-K, the Afghanistan branch of the Islamic State in Iraq and Syria (ISIS). A U.K. defense source told Sky News after the explosions that it was "highly likely" that ISIS-K was responsible for the attacks, but did not confirm its responsibility. The U.K.'s Armed Services Minister James Heapey told BBC Radio after the attacks that intelligence about suicide bombings by ISIS-K became "much firmer" and that the threat is "credible."

The Associated Press reports that U.S. officials also believe that ISIS-K had a hand in the attack. One official told AP that the group was "definitely believed" to have carried out the bombings. This attribution follows comments Tuesday from President Biden, who warned of a specific threat also from the group and the danger it posed to the U.S. and its allies in Kabul.

“Every day we’re on the ground is another day we know that ISIS-K is seeking to target the airport and attack both U.S. and allied forces, and innocent civilians," Biden said at the time.

ISIS-K began in 2014 but was officially declared by the group a year later. It has conducted numerous attacks against Afghanistan’s Hazara Shiite minorities and has clashed openly with the Taliban, who it derides as “filthy nationalists.” One Taliban official told Reuters after the explosions on Thursday that they, too, are at risk of being attacked by ISIS-K.

U.S. pressure on ISIS-K has resulted in the elimination of four of its emirs over the years, but officials warned in July that the group is still capable of conducting attacks, including against Kabul.