WASHINGTON – The Pentagon confirmed Thursday that 12 U.S. soldiers were killed and 15 injured after two suicide bombers detonated explosives near Hamid Karzai International Airport in Kabul, Afghanistan.

U.S. Marine General Kenneth McKenzie, commander of U.S. Central Command, said a number of Afghan civilians were also killed, but was unable to provide an exact number.

The explosions occurred near the airport’s Abbey Gate and the immediately adjacent Baron Hotel, McKenzie said. Several armed men opened fire on civilians and the military after the Abbey Gate explosion, he said.

The general, who oversees US military operations in the region, said the Pentagon was working to determine the attribution for the attack, but added that the bombers are currently believed to be linked to ISIS.

ISIS later claimed responsibility for the attack.

McKenzie said the US is still monitoring “extremely active threats” to the airport, ranging from suicide bombers to missile attacks. McKenzie said the U.S. emergency evacuation mission continues despite the attack.

Defense Secretary Lloyd Austin expressed condolences in a statement Thursday, condemning the attack, which “cost them their lives the moment these troops tried to save the lives of others”.

“We will not let ourselves be dissuaded from the task at hand. Doing a little less – especially now – would dishonor the purpose and sacrifice these men and women who brought our country and the people of Afghanistan,” added Austin.

About 5,400 US soldiers help with the evacuation efforts in Kabul. The British have about 1,000 soldiers helping with the evacuation. The British Ministry of Defense said no casualties had been reported to the government or the military in Kabul after the attack.

President Joe Biden will address the nation on the attacks at 5:00 p.m. ET.

“The president met with his national security team on Thursday morning, including Austin, Secretary of State Antony Blinken, the Chairman of the General Staff of the US Army, General Mark Milley, and local commanders in Kabul,” the White House said in a statement.

“He will continue to receive updates on the evolving situation throughout the day,” the statement said.

The US embassy in Kabul issued a security warning on Wednesday urging Americans to avoid the airport: “US citizens who are now at Abbey Gate, East Gate or North Gate should leave immediately,” said it in warning.

The embassy again urged Americans on Thursday not to travel to the airport and avoid its gates after the attack.

In the past 24 hours, Western forces evacuated 13,400 people from Kabul on 91 military cargo plane flights. Since the mass evacuations began on August 14, around 95,700 people have been flown out of Afghanistan.

About 101,300 people have been evacuated since the end of July, including about 5,000 US citizens and their families.

Warning: graphic image. Volunteers and medical personnel unloaded on Aug. 26 after two violent explosions that killed at least six people.

Deputy Kohsar | AFP | Getty Images

A State Department spokesman said Thursday that about 500 of the 1,500 Americans believed to be in Afghanistan have been evacuated.

“We are now in contact with the 1,000 or so Americans we believe will remain in Afghanistan. And the vast majority – more than two-thirds – have told us they are taking steps to leave the country,” added the speaker added.

Biden reaffirmed Tuesday to leaders of the G-7, NATO, the United Nations and the European Union that the United States will withdraw its military from Afghanistan by the end of the month.

The president warned that staying in Afghanistan for extended periods of time poses serious risks to foreign troops and civilians. Biden said ISIS-K, an Afghanistan-based branch of the terrorist group, posed a growing threat to the airport.

“Every day we are there is another day we know that ISIS-K is trying to attack the airport and target both US and Allied forces and innocent civilians,” he said.

The Taliban said Tuesday that the group would no longer allow Afghan nationals to leave the country on evacuation flights, nor would they accept an extension of the exit period beyond the end of the month.

“We are not in favor of allowing Afghans to leave the country,” Taliban spokesman Zabihullah Mujahid told reporters during a press conference on Tuesday.

“She [the Americans] have the option, they have all the resources, they can take with them all the people who belong to them, but we will not allow Afghans to leave and we will not extend the deadline, “he said. August would be a “violation” of a promise by the Biden government to end the US military’s mission in the country, Mujahid said.

– CNBC’s Spencer Kimball contributed to this report from New York.

This story evolves. Please check again for updates.