The boy was one of four children and two adults riding in a van travelling west on Highway 401 near Dixie at about 4:30 p.m. Tuesday.
The van was rear-ended, OPP Const. Dave Woodford told CBC News.
“The boy was sitting in the rear on the right side and it almost looks like the Hummer hit that right corner, took out the whole corner of that van and continued on," he said.
The boy was rushed to Trillium Health Centre but did not survive. The other occupants of the van were not seriously injured.
Woodford said police recovered the Hummer but are still searching for the driver.
“[The Hummer] was found by the Dixie Road area,” said Woodfood. “It was abandoned, no driver in the vehicle. Right now we have canine at the scene and assistance from Peel Regional Police looking for the driver.”
The collector lanes of the 401 westbound at Dixie were closed for several hours while police investigated.