Published: Apr 20, 2012 2:01 PM EDT

KANDAHAR, Afghanistan (AP) - An Afghan official says a U.S. Army helicopter that crashed went down in bad weather as it was racing to the site of a suicide bombing against a police checkpoint. 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. Mohammad Qayum Gorbaki, the chief of the Garmsir district of southern Helmand province, says the helicopter was en route to his area to respond to the suicide attack. He had no other details about the crash. He says the attack killed four Afghan policemen and wounded seven others.