Two people are dead following a pair of serious crashes on regional roads Sunday evening.

Ontario Provincial Police said one man was killed and a second was injured when they were struck by a pickup truck while fixing a flat tire on the side of a highway in Innisfil, about 80 kilometres north of Toronto.

Two vehicles were stopped on the right shoulder of Highway 400's southbound lanes, just south of Highway 89, when the collision occurred, police said.

It's believed a tow-truck was one of the vehicles that was stopped on the shoulder.

One man died of his injuries at the scene, while the other was taken to the Southlake Regional Health Centre in Newmarket with unknown injuries, OPP said.

Police continue to investigate and are asking anyone with information about the collision to call the Aurora OPP detachment at 905-841-5777.

Meanwhile, one person was killed and a second was injured in a crash that occurred near Major Mackenzie Drive and Islington Avenue on Sunday at about 7 p.m.

Emergency personnel had to extricate the injured person from a vehicle.