Officials confirm it was an explosion that rocked an Etobicoke jewelry store overnight, causing a massive fire that gutted the Dundas Street West shop.

The Ontario Fire Marshal's Office confirmed the explosion Tuesday afternoon, saying investigators will continue to comb the scene throughout the day for clues that will give them some more insight into how the four-alarm fire started.

At first officials said it was a Chinese restaurant that was gutted by the flames but police confirmed that the fire actually occurred inside a jewelry store at 5138 Dundas Street, located near Bloor Street and Kipling Avenue in Etobicoke. At the height of the fire, at least 10 fire trucks were on site.

Police say someone was spotted running from the scene but investigators are still trying to determine if that person had anything to do with what caused the fire or if they were just running to safety.

A man believed to be in his late 70s was helped out of the building by firefighters. He didn't sustain any injuries but he will have to find a new home, Toronto Fire Capt. Adrian Ratushniak told CP24.

Toronto Public Health has been notified and will provide the senior with assistance, Ratushniak said.

Meanwhile, emergency crews shut down the area to traffic. Dundas Street West remained closed Tuesday morning in both directions between Dunbloor Road and Michael Power Park in order to accommodate the investigation.