Three people are dead and one person has been taken to hospital, following a crash on Highway 404 in Gormley.
The two-vehicle crash happened on the northbound lanes of the highway near Stouffville Road, just before 5 p.m.
Investigators say a southbound Ford Fusion crossed the centre median and struck a northbound Toyota Camry head-on. OPP say the three occupants of the Camry were pronounced dead at the scene.
The driver of the Fusion was taken to hospital with unknown injuries.
Police have closed the northbound lanes of Highway 404 between Elgin Mills Road and Stouffville Road. One left southbound lane is also closed at Stouffville Road.
The highway is expected to remain closed for several hours.