A 22-year-old man is in life-threatening condition after he jumped onto the back of a cube van in East York and then fell and hit his head, police say.

It happened near O’Connor Drive and Donlands Avenue at around 2:15 a.m.

Police say the man was with friends when he entered the road and jumped onto the rear bumper of a southbound white cube van that was stopped at a red light.

When the light turned green, the van turned left and the man fell off, police say.

Witnesses have indicated that the man struck his head when he fell. He was later found unconscious on the roadway.

The man was taken to a trauma centre with life-threatening injuries.

The driver of the cube van, meanwhile, kept going and left the scene without speaking to police.

In a message posted to Twitter on Saturday morning, police said that investigators believe the driver may not be aware of what happened.

“The driver of the van may not have known the man was on the back of the van but we would still like to speak with him,” Det. Const. Scott Matthews said.

The intersection was closed for an extended period while police investigated at the scene. It reopened shortly after 8 a.m.

Police are asking residents, businesses, and drivers who may have security or dashcam footage of the incident to contact investigators.