Two explosions killed dozens of people, including at least 13 U.S. troops, ripping through the crowds outside Afghanistan’s main airport on Thursday, just hours after Western governments had warned of an imminent Islamic State attack and told their people to stay away from the airport.

The attack, by at least two suicide bombers, struck at the only avenue of escape for the thousands of foreign nationals and tens — or hundreds — of thousands of their Afghan allies who are trying to flee the country following the Taliban takeover and ahead of the final withdrawal of U.S. troops, set for next Tuesday.

Afghan health officials gave varying estimates of the toll at the international airport in Kabul, the capital — from at least 30 dead to more than 60, and from 120 wounded to 140 — while a Taliban spokesman cited at least 13 civilians killed and 60 wounded.