Four people were taken to hospital with respiratory issues following a chemical spill at a recycling plant in North York overnight.
Toronto firefighters responded to a call just before midnight at the Canada Fibers plant on Arrow Road near Highway 400 and Sheppard Avenue.
Fire officials said something on the conveyor line caused a noxious substance to be released in the air.
It was first reported that two people had trouble breathing. Toronto paramedics told Global News four patients were eventually taken to hospital with minor respiratory problems.
Toronto Fire said the building had to be isolated and the remaining workers inside had to be decontaminated.
Officials have yet to identify to exact source of the fumes.
Meanwhile, workers were briefly allowed back into the building to retrieve their belongings.