MONROEVILLE, Pa. (KDKA) -- A woman was killed and three others were injured in a multi-vehicle crash involving a tractor-trailer carrying an oversized load in Monroeville on Friday morning.

Allegheny County police said the preliminary investigation shows that the tractor-trailer and a Hyundai Elantra were traveling north on Mosside Boulevard. When the Elantra slowed down to make a left turn, police said it was hit by the tractor-trailer and then struck by a Dodge Caravan traveling south.

The Elantra's driver was trapped in the vehicle, police said. She was extricated and taken to the hospital, where she died.  

She was identified as 69-year-old Mary Harris of Trafford, Pa. 

A man who was her passenger was taken to the hospital in stable condition. 

Police said a man and woman in the Caravan were also taken to the hospital in stable condition. 

The driver of the tractor-trailer stayed at the scene. He wasn't hurt. Investigators said his tractor-trailer was signed as an oversized load. 

Collision reconstruction detectives are investigating.