A 45-year-old woman was rushed to hospital Wednesday afternoon after an incident on Highway 400.
OPP closed the northbound lanes of the highway at Essa Rd. for a couple hours around 4 p.m. to conduct an investigation.
The highway has since re-opened.
Initial information from police indicated a female pedestrian had been struck by a car on the highway.
But OPP Sgt. Kerry Schmidt now says the woman exited a moving vehicle and was not struck by another car.
She suffered serious injuries.
Police were speaking to the driver of the vehicle the woman was riding in.
The investigation is trying to determine what happened and why.
