WASHINGTON – President Joe Biden promised Thursday to complete the evacuation of Americans and their allies from Afghanistan after a deadly terrorist attack near Kabul airport killed more than a dozen US soldiers and many Afghans.

“We will not be deterred by terrorists. We will not let them stop our mission. We will continue the evacuation,” said Biden from the White House. “We’re going to save Americans, we’re going to get our Afghan allies, and the mission will go on. America won’t be intimidated.”

The US has approximately 5,400 military personnel helping with the evacuation effort in Kabul.

The US Central Command confirmed Thursday evening that the death toll had risen to 13 US soldiers and 18 injured after a suicide bomber detonated an explosive.

U.S. Marine General Kenneth McKenzie, commander of U.S. Central Command, said a number of Afghan civilians were also killed in the explosion, but he was unable to provide an exact number. He added that according to the current assessment of the US military, the bomber was an IS fighter.

ISIS has admitted to the attack.

Addressing those responsible for the attack, the president said, “We will not forgive. We will not forget. We will hunt you down and make you pay.”

“I will defend our interests and our people with every measure I command,” said Biden.

“I have also ordered my commanders to develop operational plans to attack ISIS-K facilities, commanders and facilities, indicating that the US had clues about the ISIS leaders who ordered the attack.

“We have reason to believe we know who they are,” Biden said, although he found the US wasn’t sure. “And we’ll find ways of our choosing, without major military operations, to get them wherever they are.”

The president warned on Tuesday that staying in Afghanistan longer than planned poses serious risks to foreign troops and civilians. He said ISIS-K, the Afghanistan-based branch of the terrorist group, posed a growing threat to the airport.

“I have repeatedly said that this mission is extraordinarily dangerous, and that is why I was so determined to limit the duration of this mission,” Biden repeated on Thursday.

Read more about developments in Afghanistan:

Earlier this week, the president told the leaders of the G-7, NATO, the United Nations and the European Union that the United States would withdraw its military from Afghanistan by the end of the month.

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.

A State Department spokesman said Thursday that the US is now in contact with the 1,000 or so Americans believed to be still in Afghanistan.

“The vast majority – over two-thirds – have told us they are taking steps to exit,” added the spokesman.