KABUL, Afghanistan – A U.S. military helicopter crashed during a firefight with insurgents in a remote area of southern Afghanistan on Thursday, killing seven Americans and four Afghans in one of the deadliest air disasters of a war now into its second decade. The Taliban claimed they gunned down the Black Hawk.

American service personnel in Afghanistan are dying at a rate of about one per day so far this year despite a drawdown of troops.

That death rate has risen recently with the summer fighting season in full gear and a rash of attacks by Afghan security forces on their foreign trainers and partners.