Two people are dead and one other is seriously injured after a head-on collision between a tractor-trailer and a car Friday afternoon.

The collision occurred on Highway 403, east of Winston Churchill Boulevard, around 3 p.m.

One person was pronounced dead at the scene of the crash, said paramedics.

A second person was pronounced dead a short time later, OPP confirmed.

One other person was transported to Sunnybrook hospital with life-threatening injuries, paramedics said.

A portion of the highway was closed east of Winston Churchill Boulevard, said paramedics.