A precautionary evacuation of residents near a sulphur plant east of Guelph ended after a few hours Thursday.
Fire chief Brent Marshall said there was a minor explosion and fire at the Holly Industries plant in Acton around 12: 30 p.m.
Marshall said the fire was put out and that no one was injured, adding that the explosion was barely noticed by workers.
Police ordered a temporary evacuation of residents downwind of the plant.
Marshall said it's not known how much sulphur was released but that the amount is believed to be small.
He said the cause of the explosion wasn't known and that investigators could not immediately enter the site.
