OTTAWA - An explosion and fire at a health-product plant in Sherbrooke, Quebec of Canada, injured 17 people on Thursday, leaving a dark cloud of potentially toxic smoke looming over nearby areas.

Police authorities said that the incident occurred in Neptune Technologies & Bioressources, a producer of health products derived from marine life like Omega-3, local media reported.

It's unclear what caused the explosion, police said, adding that within minutes, employees were evacuated from the facility and the injured rushed to hospital.

Police set up a security perimeter, closed a highway and kept people away from the area in fear of possibly toxic clouds.

Officials from Quebec environment department said the toxicity concern stemmed from the plant's acetone reserves, which were struck by the fire.

They were more concerned about the possibility of soil or water contamination than of the risk associated with breathing the air near the blast site.