The Minister of Transportation has ordered immediate changes to the lane markings on Highway 440 in the wake of a deadly crash.

On Monday at least four people died and 15 others were injured in a multi-vehicle pileup at the exit for Highway 15.

Preliminary reports from the Sureté du Quebec indicate a car merged into the exit lane very late and it was hit by another vehicle, causing the pileup.

Two tractor-trailers collided and at least two cars were crushed, while several others went off the road.

Transportation Minister Francois Bonnardel said Tuesday that he was going to order immediate changes to the lane markings so that drivers would not legally be able to change lanes so close to an exit.

"It's not going to cost a lot of money to paint a single line, to extend the single line. It will bring a little more security for this exit on this service road," said Bonnardel.

He did not say if the lane markings near other highway exits would also be altered quickly, but said they would be analyzed in the near future.

"We'll see the report from the Sureté du Quebec in the next month. After that we'll see what we can do more," said Bonnardel.

He pointed out that the area had been the scene of a dozen crashes since 2013, one of them being deadly.

"There's a lot of congestion, there's a lot of drivers who are using Highway 440 and Highway 15, about 300,000," said Bonnardel.

Laval Mayor Marc Demers said he would expect more police officers to be patrolling interchanges in the near future.

"Police departments always analyze the accident in places where there are more accidents. And normally what they do -- I was a police officer for 30 years -- they will ask for more surveillance where it's accident-prone. It's their job, their responsibility," said Demers.

He said that while traffic in Laval has increased considerably in the past decade, crashes near interchanges have not been a major problem.

In the meantime police have spoken to several of the survivors of Monday's crash, and the SQ is still canvassing for witnesses.

Autopsies will be necessary to identify some of the victims.

With reporting from Cindy Sherwin