A suicide bomb attack Thursday outside the Abbey Gate at Kabul's airport in Afghanistan killed 13 U.S. service members and injured at least 18 more, U.S. officials said – making it the deadliest day for U.S. troops in 10 years.
Officials told Fox News late Thursday that those killed included 10 Marines, two Army soldiers and a Navy corpsman, correcting earlier reports that 12 Marines were killed.
The suicide bomb attack was followed up by a firefight by Islamic State gunmen at the gate, where the night before there had been 5,000 Afghans and potentially some Americans seeking access to the airport to flee. Crowds had gathered for days seeking to escape the country, and there had been multiple warnings of a terror threat to the area – particularly from the Islamic State.
The Pentagon confirmed the initial explosion as well as a second attack at the Baron Hotel, where Americans have gathered in the past for rescue and evacuation. Marine Corps Gen. Kenneth McKenzie Jr. said two suicide bombers were assessed to be ISIS fighters.
"The threat from ISIS is extremely real," he said. "We believe it is their desire to continue those attacks, and we expect those attacks to continue, and we're doing everything we can to prepare for those attacks."
Defense Secretary Lloyd Austin issued a statement on the attacks.
"On behalf of the men and women of the Department of Defense, I express deepest condolences to the loved ones and teammates of all those killed and wounded in Kabul today," he said. "Terrorists took their lives at the very moment these troops were trying to save the lives of others."
"We mourn their loss. We will treat their wounds. And we will support their families in what will most assuredly be devastating grief," he said. "But we will not be dissuaded from the task at hand."
More than five hours after the attack, President Biden had still not issued a statement about the attack. He is scheduled to speak at 5 p.m. ET.
It was not clear the extent of the injuries suffered by the troops, and how many others were hurt in the large crowds that regularly gathered at the airport seeking to flee the Taliban.
However, it marks the deadliest day for U.S. troops since insurgents in Afghanistan shot down a U.S. Chinook helicopter in August 2011 – which killed 38 people, including 31 U.S. troops.
The Taliban had moved quickly through the country ahead of the planned U.S. withdrawal at the end of the month, catching the U.S. off guard and leading to chaotic scenes at Kabul airport and a mass evacuation effort. As of Thursday, 104,000 people had been flown out, including 5,000 U.S. citizens. The Pentagon said about 1,000 Americans may still be in the country.
There are currently 5,200 U.S. troops at the airport and thousands of Afghan evacuees still on the tarmac waiting to be evacuated. U.S. planes have been leaving every 40 minutes out of the airport.
A source briefed on the situation told Fox News that there are hundreds of Islamic States fighters in the vicinity and warned that attacks are "likely to continue."
"Taliban has essentially completely stopped letting Afghans through," the source said, adding that they are "mostly" letting Americans through, but many are staying away due to the ISIS threat.
"Military continues to retrograde and depart airport. Almost a certainty that Americans will be left behind," the source said. "They will have to be extracted after the fact through either Taliban negotiation or unconventional means."
President Biden had faced significant pressure, both at home and from international allies, to delay the withdrawal date, but has so far pledged to stick to that timeline. Former President Donald Trump issued a statement, sending "deepest condolences to the families of our brilliant and brave Service Members whose duty to the U.S.A. meant so much to them."
"Our thoughts are also with the families of the innocent civilians who died today in the savage Kabul attack," he said. "This tragedy should never have been allowed to happen, which makes our grief even deeper and more difficult to understand."
The bombing came hours after the State Department warned Americans outside the gates of the Kabul airport to "leave immediately" due to the increasing terrorist threat. Blinken had said Wednesday there was a "very real possibility" of an attack.
In an alert on Thursday, the State Department confirmed a large explosion and reports of gunfire and said: "U.S. citizens should avoid traveling to the airport and avoid airport gates at this time."
"U.S. citizens who are at the Abbey Gate, East Gate or North Gate now should leave immediately," the bulletin said.
A White House official told Fox News that President Biden has been briefed on the explosion. Biden had been scheduled to meet with his national security team Thursday morning. Vice President Harris has also been briefed on the situation.
Fox News' Chad Pergram and Jacqui Heinrich contributed to this report.