KANDAHAR, Afghanistan (AP) — A U.S. Army helicopter has crashed in Afghanistan, killing all four American crew members.

The U.S. military confirms that the chopper went down last night as it was responding to a suicide attack at a police checkpoint in Helmand province. A district chief there says the aircraft went down because of bad weather, though U.S. officials say they haven't determined the cause of the crash yet.

Defense officials in Washington confirmed that the four killed in the chopper crash were American troops.

The Afghan official says four Afghan police officers and seven other people were killed in the attack on the check point.