An explosion and fire at a plant sent 17 people to hospital, four of them with serious injuries, and produced a dark cloud of toxic smoke Thursday.
The incident occurred in Quebec's Eastern Townships at a facility belonging to Neptune Technologies & Bioressources, which produces health products derived from marine life like Omega-3.
A Sherbrooke police spokesman said the explosion triggered the fire. Police couldn't immediately say if any lives were in danger.
"It's a major fire. There are a number of injuries," said Rene Dubreuil of the Sherbrooke police.
"For now we're trying to secure the area and take care of the injured."
A fire department spokesman said that all 65 employees had been accounted for. In the minutes following the blaze several people were feared to be missing, but they were later found.
Environment Quebec said the toxicity concern stemmed from the plant's 15,000-litre acetone reserve, which was struck by the fire.
Acetone is flammable and, when ingested, can cause irritation.
Officials said they were actually more concerned about the possibility of soil or water contamination than of the risk associated with breathing the air near the blast site.
It's unclear what caused the explosion.
"It's too early to tell right now. Our investigators will have to figure out the point of origin as well as what caused it," said Gaetan Drouin, a local fire chief.
There was at least one large explosion followed by a series of smaller explosions. Drouin said the initial explosion was violent and set a local record for 911 calls.
About 50 firefighters were on scene.
Within minutes, police said, employees were evacuated from the facility and supervisors performed a head count outdoors.
Police then set up a security perimeter, clearing the industrial park.
"We're asking people to stay away from the area. These are possibly toxic clouds," Dubreuil said.