LEWISTON, Idaho (KTVB) -- Idaho State Police say a 29-year-old Boise man fell asleep at the wheel and crashed into the Lochsa River along Highway 12 early Wednesday.

Two passengers in the vehicle are believed to have died in the river, according to police. The crash happened just before 3 a.m. near milepost 97, which is located near the town of Lowell. Sgt. Rich Adamson says Boone Hallmark was eastbound in a 2003 Chrysler PT Cruiser when he fell asleep and went off the south edge of the highway.

The car submerged in the river. Hallmark was wearing a seatbelt and managed to escape. He was transported to Syringa Hospital in Grangeville. Two passengers, an adult female and a young child, were in the vehicle. Adamson says police have been unable to get to the vehicle because the river conditions are fast and high.

Officers are still on scene and plan to remain there until they can get the car out of the river and recover the bodies. The Idaho County Sheriff's Office and Idaho Department of Transportation provided assistance to police. The cause of the crash remains under investigation.