Environment Canada has issued a freezing rain warning for much of southern Quebec, including Montreal and Laval.

René Héroux with Environment Canada said the weather system is weak but could still be dangerous. He said people should be very cautious if they're heading outside.

Héroux said a low-pressure system from Texas is expected to bring up to 10 millimetres of freezing rain on Wednesday.

"Since there is no snow on the ground, it freezes everywhere. It could be on the sidewalk, on the street," said Héroux.

The conditions caused several accidents in Montreal Wednesday, including a serious accident north of the city, along Highway 148 in St-Eustache.

An ambulance and a car slid on the road and crashed into each other.

The car flipped over and the driver was sent to hospital with serious injuries.

Dozens of cars and a few trucks also slid off the road Wednesday.

On the west island, Highway 40 was closed in both directions at des Sources Boulevard because of a multi-vehicle pile-up.

The left lanes in both directions on Highway 20 at St-Charles Boulevard were also closed after a truck heading west slid off the road and crashed into the fence.

On the South Shore, several vehicles flew off the road on the Highway 132 west at Roland-Therrien Boulevard.

And in Laval, there were several cars off the road on both Highway 13 and Highway 15.

Transport Quebec and the city of Montreal said Wednesday that sanding operations are under way.

For a full list of Quebec road closures, go to Quebec511.