Provincial police are calling for a review of Ontario's seatbelt law in the wake of a fatal crash involving an overloaded minivan which killed four people.

The four died when a packed minivan collided Saturday with a tractor-trailer near Caledon, in a rural area northwest of Toronto. Police said 10 people were in the vehicle.

In Ontario, it's legal to carry more passengers in a vehicle than there are seatbelts as long as all seatbelts are being used and the driver is not inhibited by any of the passengers.

Transportation Minister Donna Cansfield agrees that the decades-old law needs to be changed so that the number of passengers in a vehicle matches the number of seatbelts.

Police have not identified the victims of Saturday's crash, but nine are visitors from South Korea and one is a local woman, police said.

Language barriers have made it difficult for police to identify the victims and notify next-of-kin.

Investigators are still piecing together what caused the collision on Mississauga Road at Charleston Sideroad, but don't believe weather was a factor.

The flaw in Ontario's seatbelt law was highlighted by another fatal collision nearly a year ago when a 13-year-old Ottawa boy died after being ejected from an SUV. He wasn't wearing a seatbelt.

Eight people were packed into the SUV, but there were only five seatbelts.

In Quebec, the law restricts the number of people in a vehicle to the number of seatbelts available.