The investigation continues today into an explosion that reduced a Pickering home to rubble on Monday afternoon.

It was shortly before 2:30 p.m. when a sudden blast levelled a house near York Durham Line and 16th Avenue.

Thick plumes of black smoke billowed above the debris, which was strewn across the large property.

Firefighters arrived to find the lot “fully-involved” in flames and began working to control the blaze.

Officials said a 32-year-old man was inside the home when it blew up. He was discovered at the scene with severe burns and was rushed to hospital in critical condition, where he remains.

On Tuesday morning, shocked neighbours visited the property, where only the front gates still stand.

“It was a gorgeous home. Now it’s gone, totally gone,” neighbour Judy Grant said. “I just hope the fellow is okay.”

Investigators with the Ontario Fire Marshal (OFM) took over the investigation and worked overnight to try and determine a cause.

“At this point in time we did determine that the natural gas was not on this site. We still haven’t determined what other sources of ignition or fuel source could have caused this explosion,” Ontario deputy fire marshal Douglas Browne said.

“We know there is propane on the site, but I won’t comment if that was the source to the fuel for the explosion. We haven’t made that determination at this point in time.”

While there is no question an explosion occurred, Browne said investigators are still trying to confirm which occurred first – the blast or the fire.

Investigators will use machinery to comb through wreckage for evidence this afternoon.

At the height of the fire, five fire trucks from Ajax, Markham and Pickering were on scene.