Approximately 40 homes were affected by a fatal blast caused by an unknown gas that flattened a two-storey Scarborough home and showered the neighbourhood with debris.

The explosion happened at 3356 Brimley Rd., near Steeles Avenue, shortly before 4:30 p.m. on Monday. The man found dead at the back of the home was later identified as 57-year-old Paul Zigomanis. A post-mortem examination was scheduled to take place Tuesday morning.

Speaking from the scene Tuesday, an investigator with the Office of the Ontario Fire Marshal said there’s more than a metre of debris that crews have to sift through at the site.

"Those (homes) closest to the blast really sustained the most structural damage," Wayne Romaine told reporters.

He added at least six residences have had "orders placed against them" and the occupants will have to work with the city's building department and their insurance company before reoccupying their homes.

"A structural engineer will be required at each home affected to determine its integrity," Romaine said. "Cracks and everything will have to be assessed."

Romaine didn't have an estimated cost of the damage.

Earlier Tuesday, Romaine said investigators are working with forensic and canine officers, firefighters, and structural engineers to determine the type of fuel that led to the explosion.

"We're slowly, methodically trying to develop an investigational plan," he said.

"It is unclear at this time what fuel created this explosion," Romaine said, adding it was some kind of "volatile, ignitable liquid."

Romaine said the lack of fire damage on most of the debris in the area indicates that whatever fuelled the explosion was spent in the blast, burning so quickly that the flames didn't reach most of the home.

The two-storey home was completely destroyed. A firefighter who responded to the scene said it resembled a "war zone," with pieces of wood, drywall and insulation scattered for hundreds of metres.

Due to the amount of debris, Romaine said investigators still aren't sure whether anyone else is buried in the rubble. But he said no one has been reported missing so far. A fourth police dog was brought in to help in the search Tuesday morning.

"The debris field is massive," he said.

Toronto Fire Services said there was a natural gas leak in the area for several hours following the explosion. A representative of Enbridge Gas said the leak had been stopped overnight.

Police said they weren't sure whether the explosion was caused by some type of criminal act.

"There's no indication that this is any sort of drug or meth lab at this stage of the game," Toronto Police Insp. David Vickers said Monday evening.

"We're going to be going through the scene with Toronto Fire and with our forensic identification bureau to see if there's any indication to that effect… We're treating this as a crime scene."

The victim of the fire was wanted by Toronto Police for assault and death threats dating back to November 2013.

In a post on Facebook, police said Zigomanis was wanted on two counts of assault causing bodily harm, and one count of uttering death threats. At the time, police wrote it was alleged that he had known the victims for several years and the assault was over a monetary dispute.

Anyone with information about the explosion is being asked to contact the officers at Toronto Police's 42 Division at 416-808-4202.