A woman is dead after an SUV drifted into oncoming traffic and collided with a transport truck on a highway located northwest of Toronto.

OPP Sgt. Kerry Schmidt said the female driver was pronounced dead at the scene. The head-on crash happened near Schomberg, Ont., on Highway 9, near 12th Concession, shortly after 3 p.m. Schmidt said the woman’s Chevrolet Equinox was heading east on the highway. It drifted into the westbound lanes and collided with the transport truck.

Schmidt said the truck attempted to swerve around the vehicle, but ultimately hit the SUV on the driver's side. He said it is unclear why the woman's vehicle drifted into oncoming traffic.

OPP have identified the woman as Dena Passero, 44, from Tottenham, Ont.

Hwy. 9, between Concession Road 11 and 12th Concession was temporarily closed as OPP investigated the crash.