Ontario Provincial Police say they have learned about more incidents of rocks being thrown at vehicles on Highway 48 in Markham.

On Sept. 20, a rock thrown at a moving vehicle in the area of Highway 48 and Major Mackenzie Drive caused a collision that sent two people to the hospital with life-threatening injuries, police said. Earlier that night, officers also got two separate reports of rocks hitting vehicles on the highway just north of Elgin Mills, leaving two drivers with minor injuries.

Police have since received a report of a fourth similar incident that same night. A vehicle travelling north on Highway 48 just past Major Mackenzie Drive was hit by a rock that damaged the driver's side-view mirror.

Investigators have also found out about two similar incidents on the evening of Sept. 12. One was a vehicle travelling south on the highway near Stouffville Road and was hit by a rock, which smashed the driver's side headlight.

The other involved a vehicle travelling north on the highway near Elgin Mills. A rock struck the vehicle, wrecking the driver's side-view mirror.

Police said investigators believe all the incidents are linked to the same person and vehicle. They urge anyone with information to contact them at 1-888-310-1122 or Crime Stoppers anonymously at 1-800-222-TIPS (8477) or ontariocrimestoppers.ca.

With files from CTV News Toronto's Alex Arsenych