The US ambassador to Kabul said four US Marines were killed in an explosion at the city's airport and three were injured. Two explosions thundered in a crowd of Afghans trying to enter the airport on Thursday, according to The Wall Street Journal.

At least three more US military personnel were injured, a US official said. Witnesses reported numerous Afghan casualties, many of whom tried to break into the airport because they aided the efforts of the US-led coalition and feared Taliban persecution.

The bombing at the airport entrance was the result of a complex attack, said Pentagon spokesman John Kirby. He said that another explosion occurred near the Baron Hotel, adjacent to the airport. A British security official said both attacks were carried out by suicide bombers.