Emergency crews began removing small sections of a collapsed overpass in Laval, Que., as hope faded late Saturday for at least two people feared dead in vehicles trapped under a massive slab of concrete.

Jean-Claude Beaudry, a City of Laval spokesman, told the CBC earlier in the evening there were probably one or two dead people buried in the debris.

Emergency crews were working to free at least three vehicles from the rubble of the collapsed overpass.
(CBC)

Laval rescue officials have seen two vehicles beneath the rubble, but don't know how many people are trapped inside, fire Chief Robert Seguin said.

Engineers from Transport Quebec decided to cut the 20-metre segment into about a dozen smaller pieces instead of trying to raise the collapsed portion in one piece, CBC Newsworld's sister station RDI reported Saturday evening. The effort was expected to continue well into the night.

"We're very anxious to know how many people are trapped under and what condition they're in," said André Champagne, a spokesman for the Urgences-Santé paramedics service.

The teams had to wait several hours to ensure that the remainder of the structure was not in danger of collapsing.

'House of cards'

Three vehicles and a motorcycle fell about 15 metres on to Highway 19 from Boulevard de la Concorde after three lanes of the overpass gave way just after noon ET Saturday. Six people were injured, with two listed in critical condition with head, chest and abdominal injuries, police said.

Manon Joly was driving on the overpass when she saw the segment fall.

"I slowed down and then all of a sudden everything collapsed like a house of cards," she said. "There were three or four cars that plunged into the hole right in front of me."

Another motorist recalled looking in his rear-view mirror and seeing the collapse.

"I was just ahead of them, maybe five minutes ahead and I just saw smoke," said Gino DeCaprio.

Transport Quebec spokeswoman Josée Seguin told the Canadian Press the overpass was built in 1970, but she didn't know when it was last inspected.

She said the department heard about an hour before the accident that pieces of concrete were falling off the overpass. Transport Quebec then issued an advisory to some media, she said.

Vehicles under rubble

Several hours after the collapse, emergency crews wrapped steel cables around one of the concrete chunks and attempted to lift the piece off crushed vehicles with two huge cranes.  

The rear half of a van could be seen protruding from the rubble, along with part of a car. Another car was lying on its side, stuck between chunks of concrete.

The routes involved include a major highway connecting Laval with the island of Montreal.

Police are advising motorists to stay clear of the area. Highway 19 and Boulevard de la Concorde have both been closed to traffic.

Lost bond may have caused collapse

Shamim Sheikh, a structural engineer with expertise in bridges, told the Canadian Press that steel bars inside the overpass likely lost their bond with the surrounding concrete and left the section of roadway unable to support its own weight.

"For 30 years this bridge was sitting there and it worked very well, so the structural system was fine, there was no issue with the design," said Sheikh, who teaches engineering at the University of Toronto. "The maintenance of the bridge should have picked up any weaknesses."

The collapse is not the first in the Laval area. In 2000, a large segment of an overpass on Highway 15 collapsed, killing one motorist instantly and trapping two others for several hours.

A coroner's report later concluded a construction company had not properly secured the concrete beams, and accused the province's construction industry of shoddy work and questionable corporate practices.

"I don't know what's happening in our city," DeCaprio said.

With files from the Canadian Press