Motorists around Toronto faced a nightmarish commute home on Thursday after two separate accidents -- one fatal -- shut down two sections of Highway 400 in the early afternoon.

The driver of a tractor-trailer was killed in the first accident that occurred just after 1 p.m. in the southbound lanes under the Finch Avenue overpass.

Provincial police said a car spun and hit the rig, which ejected the male driver. He was pronounced dead at the scene.

"He went into the guardrail, tore out a section, the truck flipped right around in the air and then the fence tore him right out of his seat," said a truck driver named Dean, who witnessed the horrific crash.

Sgt. Cam Woolley said the driver was wearing his seatbelt, but it couldn't save him because the victim was "ripped from the cab."

The occupants of the car were taken to hospital with minor injuries.

Police said the highway was clear at the time, but wet.

Another accident at about the same time, in the northbound lanes at Highway 7, also caused a massive backlog of traffic. That crash happened when two cars collided, and one of the vehicles was sent into a tractor-trailer.

An air ambulance landed on the highway to take away a male victim who suffered life-threatening injuries. He is listed in critical condition.

The sections of highway were expected to be remain closed until mid-evening.

The incidents occurred hours after the OPP recorded hundreds of accidents during the first winter storm of the season. As much as 15 centimetres fell in cities around the GTA.

With a report from CTV's Roger Petersen