April 20, 2012 10:23 AM

AP) KANDAHAR, Afghanistan -

A U.S Army helicopter crashed in bad weather during a night flight in Afghanistan, and all four American crew members were killed, U.S and Afghan officials said Friday.

The American military has confirmed the chopper crashed Thursday night while responding to a suicide attack on a local police checkpoint.

A U.S official in Washington confirmed Friday that four Americans on board were killed. The military said the cause of the crash was not known, and no other details were immediately available.

The chief of the Garmsir district in southern Helmand province, Mohammad Qayum Gorbaki, said the helicopter was flying to the scene of a suicide bombing in his area when it crashed late Thursday because of bad weather. He had no further details about the crash.

Gorbaki said four Afghan police officers were killed and seven others were wounded in the suicide attack on the checkpoint.

Two U.S defense officials in Washington said late Thursday that four American troops were aboard the helicopter, identified as an Army Black Hawk.  

All the officials spoke on condition of anonymity because details were still being collected, and the families of the helicopter crew had not yet been notified.