Police have launched a criminal investigation after two vehicles were in a head-on collision on Highway 3 just east of Walker Road around 9:15 a.m Wednesday.
Firefighters extricated trapped people from the two cars. Four people were sent to hospital.
Initial reports from police said three vehicles and a transport truck were involved, but police later clarified the transport and one of the vehicles in the area were driven by witnesses to the collision.
Police blocked off Highway 3 between Oldcastle Road and Sexton Sideroad until just after 4 p.m. and said injuries from the collision ranged from serious to critical.
The OPP canine unit was on scene and the dog appeared to be focused on the back seat and trunk area of one of the vehicles.
Police would not comment on why they were searching the car. OPP said that two people involved in the collision were taken into police custody.
Motorists are advised to avoid the area and seek alternate routes.