An Afghan guard was shot dead early Monday after a firefight involving U.S. troops broke out during the ongoing evacuation chaos at Kabul airport, according to Germany’s armed forces. The Bundeswehr said in a statement that gunfire between Afghan security forces and “unknown attackers” erupted at the North Gate of the airport, killing one member of Afghan security and injuring three others. U.S. and German troops were involved in the battle, the Bundeswehr said, but it didn’t elaborate on what role those troops played. CNN’s Nick Paton Walsh reported that the gunfire began when an unidentified sniper fired on Afghan security, who then shot back toward U.S. marines, who returned fire. The U.S. military hasn’t released any details about the incident. Thousands of Afghans and foreigners remain at the airport as they try to flee Taliban rule.