As American troops continued evacuation efforts in Afghanistan, militants attacked Hamid Karzai International Airport on Thursday, killing more than 90 civilians attempting to flee Taliban rule and 13 U.S. troops.

“Today’s heinous attack at HKIA further accelerates the urgency of our mission to remove U.S. troops, American citizens and our Afghan allies from Afghanistan,” said Hawaii U.S. Rep. Kai Kahele, a veteran of the conflict, in a statement released on social media.

Islamic State Khorasan, an Afghan offshoot of the Islamic State group that briefly established a caliphate in Iraq and Syria, claimed responsibility for the attack. The group has fought against both U.S. forces and the Taliban — both of which have unofficially cooperated in hunting down and killing members of the group.

It’s the bloodiest attack on the U.S. military in Afghanistan since the 2011 downing of Extortion 17 — a helicopter carrying American and Afghan special operations troops — killed all 38 people on board.

“What we can do right now, is offer our support and respect to all the mothers, fathers, spouses and children around the world who anxiously wonder whether or not their loved ones serving in Afghanistan are safe,” said Kahele.

The U.S. government and the Taliban signed a peace agreement last year and in April the U.S. military began what was supposed to be its final withdrawal.

Some lawmakers and veterans, including Kahele, urged President Joe Biden to begin evacuations of Afghans fleeing the Taliban while U.S. troops were still in the country. However, the administration waited until after closing all U.S. bases and only began airlifts in late July under pressure from veterans groups and veterans in congress.

This month the Afghan government collapsed as Taliban fighters took over the capital and desperate civilians — both Afghans and foreign nationals — rushed to the airport trying to flee. There are now more troops in Afghanistan supporting the evacuation than when Biden took office.

Several charter flights booked by American veterans, aid workers and others to get Afghan friends and colleagues out have been leaving nearly empty as Taliban and military checkpoints block many Afghans from leaving.

The evacuation is set to end on Aug. 31 in an agreement with the Taliban, though there are concerns thousands will be left behind.