Military officials say a helicopter has crashed on an Army base in Louisiana, killing one person and injuring three others.

Fort Polk officials said in a statement that the Army chopper crashed early Thursday morning in the Fort Polk training area.

Base officials say there were the four crew members on board. Their names weren’t being released until relatives are notified.

The fort said the cause of the crash is under investigation.

No further details were immediately released.

About 8,000 soldiers are stationed at Fort Polk, its website states. The base is in central Louisiana, about 150 miles (240 kilometers) northwest of Baton Rouge.