Police say they will work night and day to find two workers presumed to be buried under rubble after a landslide at a quarry near l'Épiphanie, Que., 50 kilometres north of Montreal.

Repentigny police Sgt. Bruno Marier said Wednesday between 60 and 80 workers would continue searching the grounds overnight in hopes of finding the two missing people.

Marier said the crews faced challenges when trying to bring equipment down the 100-metre-deep quarry. He said a loader had been brought on site safely and would be used to excavate.

Earlier Wednesday afternoon, a dog from the K-9 unit reportedly discovered four areas of interest. Provincial police said searches yielded no results.

Marier said workers had been given avalanche alert systems as a precaution.

Quebec's Public Security Minister Stéphane Bergeron said the rules put in place by the workers' health and safety board (CSST) did delay the rescue work this morning but will keep people safe on the unstable terrain.

"Yesterday, we had to interrupt the operations because the CSST wanted to be sure that all this operation could be conducted under the parameters that will ensure the security of the personnel. We have been able to start again the operations this morning," he said Wednesday.

Bergeron said the search will carry on until the people are found.

Survivor speaks

Benoît Robert, the loader operator who was rescued, spoke to media Wednesday from the hospital in Terrebonne, Que., where he was recovering from the shock of his ordeal.

Barely holding back tears, he recalled being inside the cab of his loader, in the process of filling up a truck when he saw the ground began to shake.

At first, he said, he thought he was having problems with his vision.

Robert said that's when the woman in the truck said to him, "We're sliding. We're going to die."

He said his loader fell seven to eight metres before stopping. Robert said he thought about jumping from the vehicle, but as he watched an avalanche of rubble cascading down the side of the quarry right in front of him, he said he knew he would be killed if he tried to escape the cab.

He said the loader fell about another 100 metres before it came to a stop, and he was able to get outside.

"I was lucky," he said.

Soon after, he scrambled over to the partially buried truck and called out, asking if anyone was there.

But Robert said he heard no response.

He thanked the police, his co-workers and paramedics for their help and support.

Robert said he was grateful to be alive.

"It's difficult, what I lived through, but I am still here," he said.

Doctors confirmed Robert he did not suffer any physical injuries in the landslide.

He said his employers, Maskimo Construction and Excavations G. Allard, are caring and would have never sent him deliberately into a dangerous situation.

Robert said he sends his best wishes to the families of the missing workers.

"I don't know if they'll be there in the future but I know the family is still there and they could live difficult moments," he said.

Two still missing

On Tuesday, three workers fell into the large gravel quarry after a landslide carried two trucks and a loader and buried them at the bottom of the pit. One man, who only suffered minor injuries, was rescued yesterday by helicopter.

Family members gathered at the site Wednesday as search-and-rescue efforts continued for a man and a woman who are still missing.

"At this time we still have hope, but it's more of a recovery mission than a safety mission now," said Marier.

Using metal detectors, thermal cameras and search dogs, rescue workers continued their search Wednesday after halting operations overnight because of dangerous conditions.

This morning, a crane was on its way to the quarry, where it will be used to help lower equipment needed to dig through the rubble. (CBC)

On Tuesday, crews were able to uncover and peer into one of the trucks buried under the rubble, but officials said that it was empty.

Rescuers have been unable to reach the second truck's cabin.

Marier said the next step is to use an excavator, which is already at the bottom of the pit, to help dig around the buried trucks.

A crane on site will lower a bucket down to the excavator. The bucket will then be attached to the crane and used to help sift through the rubble.

Rescuers face with risky conditions

Marier said it's possible the two people managed to jump out of their trucks when the landslide occurred.

"That's the problem, we don't have any information if the two occupants of both vehicles were able to get out of the vehicles when the landslide happened," he said.

Marier said experts believe the landslide was followed by an avalanche of mud, which has made rescue efforts especially challenging.

Crews are dealing with many obstacles, especially the unstable, muddy ground, which Marier said could jeopardize the safety of rescue workers.

Investigators are looking into the cause of the landslide, which remains unknown.