BOSTON (AP) – Three fatal accidents in as many days claimed the lives of four young people, including a 14-year-old Milford boy, on Massachusetts roads this weekend.

The Milford boy died early Sunday morning when the car he was in struck a sign post at the on-ramp to the Massachusetts Turnpike in the Brighton section of Boston, state police said. The 20-year-old driver was seriously injured.

Early Saturday in Worcester, Amber Bird, 19, and Luis Rivera, 21, died in an accident on East Mountain Street. Bird was driving and tried to make a U-turn, but her car was struck by a vehicle behind her.

On Friday night, a 17-year-old boy died in an accident on Interstate 495 in Berlin.

State police said he was a passenger in a car containing four other young people. The boy was not identified.

The car was driven by Jorge Pena, 18, of Haverhill. It hit a wall along the southbound ramp from I-495 at Route 62. Pena suffered serious injuries. He was being treated at UMass Memorial Medical Center.

No charges have been filed in the accidents. The causes remain under investigation.