Maine State Police say four people sustained minor injuries late Tuesday night when a charter bus overturned on Interstate 95 just north of Waterville.

Troopers said the bus driver fell asleep at the wheel and the bus drifted off the right side of the highway, flipped on its passenger side and came to rest down an embankment.

The crash happened around 11:30 p.m. in Burnham. Three women and a man, all in their 20s and 30s, were taken to hospitals in Pittsfield and Waterville for treatment.

The 34 other passengers and the driver were transported to a Waterville motel for the night.

The group from Schenectady, New York was headed to Orono for a Christmas concert Wednesday night.

State Police cited the driver of the charter bus–65 year old Charles Barry of Omaha, Nebraska–for failing to maintain control of the vehicle.