GUELPH, Ont. - Ontario's police watchdog is investigating after police allege a pedestrian died when she was hit by a vehicle fleeing from a RIDE spot-check.

The Special Investigations Unit says the collision occurred at about 3 a.m. Sunday.

Police in Guelph, Ont., say an OPP officer was attempting to stop a vehicle to conduct a RIDE check, but the driver failed to stop.

They say the officer followed the vehicle's route, and found the vehicle hit the pedestrian and the unknown driver fled the scene.

The SIU says the 24-year-old woman was gravely injured. She was taken to hospital and pronounced dead.

The agency says six investigators and three forensic investigators will probe the incident.

The agency is automatically called in to investigate reports involving police where someone is killed or seriously injured.