A mother and her young child are dead following a multi-vehicle crash in Caledonia Friday afternoon, Ontario Provincial Police have confirmed.

OPP Const. Mark Foster said the six-vehicle crash happened on Highway 6 just before 3 p.m.

According to police, an SUV was travelling northbound on the Highway 6 bypass approaching the Grand River Bridge when for unknown reasons it entered the southbound lane and was struck by a transport truck.

The resulting impact forced the SUV to collide with four other vehicles, police said.

The 28-year-old female driver of the SUV was ejected during the collision, sustaining fatal injuries.

Her three-year-old son travelling in the vehicle sustained life-threatening injuries.

He was transported to hospital where he later died.

Their names have not been released.

The other five drivers involved in the collision were uninjured, police said.

The area is currently closed as police investigate the circumstances surrounding the crash.