MANSFIELD, Mass. (AP) — State police are trying to determine what caused a car to go off Interstate 495 and crash into trees in Mansfield in an accident that killed one person and injured two others.

Troopers say several people called 911 shortly before 6:30 p.m. Saturday to report that a car went off the northbound side of the highway near exit 13. Witnesses said the car drifted into the breakdown lane and crashed into the tree line.

Several motorists stopped to help, including some who performed CPR on one of the victims.

The victims' names haven't been released.

One victim died at a nearby hospital. Another is being treated for life-threatening injuries at Brigham and Women's Hospital in Boston. The third person was taken to a hospital with non-life threatening injuries.