The person killed in a crash between a car and dump truck on Highway 9 west of Newmarket on Tuesday afternoon was a 20 year old Barrie man.
He was the passenger in the car, while the driver, a 19 year old Barrie man, is in life-threatening condition.
The driver of the dump truck suffered minor injuries.
York Regional Police said the collision happened at Highway 9 and Jane Street around 2:20 p.m.
Anyone who may have been a witness or has dashcam footage of the collision is being asked to contact police.