the pentagon calling the blast a, quote, complex attack with one suicide bomber setting off explosives while being searched at the gate to the airport. u.s. service members killed are the first american casualties in afghanistan in 18 months. in a statement defense secretary lloyd austin said in part, 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. but we will not be dissuaded from the task at hand. an affiliate of isis has claimed responsibility of the attack, believed to be an adversary of the taliban. it came hours after western governments issued multiple warnings about the possibility of a terror attack. the u.s. embassy in kabul last night urging americans to stay away from the perimeter of the airport. the situation remains very fluid. the president has been briefed on the situation and is expected to speak in the next hour. we're going to bring that to you live when it happens.