KANDAHAR, Afghanistan – A U.S. Army helicopter crashed in bad weather during the night in Afghanistan as it was en route to respond to a suicide attack on a local police checkpoint, an Afghan official said Friday.

The American military has confirmed the Black Hawk crashed on a nighttime mission Thursday, and initial reports indicated that as many as four soldiers may have been killed. It said the cause of the crash was unknown.

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, and one official said initial word from the scene was that officials “don’t expect” that any of the four survived. Both officials spoke on condition of anonymity because details were still being collected and the families of the helicopter crew had not yet been notified.

In a brief official announcement, the American military command in Kabul said there were “no confirmed reports” of casualties “at this time.” The announcement did not specify the nationality of the helicopter crew and said the cause of the crash was unknown.