Four unstrapped teenagers are in serious condition after their speeding vehicle turned turtle and caught fire early Sunday morning on Highway 401. The four were part of the seven occupants of the van saved by off-duty Canadian Force medic Patrick Chatelain, who happened to pass by.

The three others who had seatbelts sustained minor injuries, underscoring the importance of seat straps in saving travelers' lives. The four were thrown all over the highway. Two were prone on a grassy ditch, one slumped against the guardrail and another on the middle of the express lanes.

Chatelain was assisted in assisting the accident victims by three other off-duty paramedics and an off-duty officer also coincidentally in the same place.

Two of the badly injured passengers were rushed to the Sunnybrook hospital and underwent emergency treatment.

The seven were on their way home from a dinner aboard a Pontiac Montana van owned by the father of one of them. Their van was overspeeding, but the driver and the passengers were apparently not drunk, Constable Dave Woodford told the Toronto Star.

Only two of the seven accident victims were identified, Rasheed, 19, and Farhad, 16. The driver, a 20-year old, was arrested and charged wth dangerous operation of a motor vehicle.

Canada has a seat-belt law that requires mandatory strapping while on board a vehicle. Compliance is high, with 9 in 10 Canadians following the law. For violators, Louis Francescutti, an injury researcher at the University of Alberta and an emergency doctor, proposed slapping them with a $990 (1,000 Canadian dollar) fine or charging them for the hospital bill if they are injured.

"Society is not getting the message that motor vehicle accidents are the leading cause of death for Canadians under the age of 34," Francescutti told the Globe and Mail.