TORONTO -- A house fire in Markham has sent two children and one adult to hospital and police say have not yet located two other occupants of the home.

Officers responded to the area of Bur Oak Avenue and Kennedy Road at around 10 a.m. Sunday for reports of a fire and possible explosion.

It is believed that the fire started inside a townhome in the area and quickly spread to adjacent residences.

York Regional Police Sgt. Andrew Bell told reporters at the scene that some witnesses reported hearing a “very loud” bang before the fire broke out.

“I can't say definitively that it was an explosion, but consistent with something like an explosion,” he said.

Two children, a 14-year-old boy and a six-year-old girl, were rushed to hospital along with an adult female.

Police previously confirmed that the three victims all sustained burn injuries.

Bell could not say if the woman who was injured is the mother of the two children.

House fire, Markham

According to police, two other occupants of the home have not yet been accounted for.

“We are still trying to locate these people. We don't know their whereabouts at this point in time. We physically haven't been into the structure yet,” Bell said, adding that there are some concerns about the structural integrity of the building.

Bell said so far there is nothing to indicate that the fire is suspicious in nature.

“Our criminal investigations branch is heading up the investigation,” he said.

“We have canvassed for witnesses. We are currently reviewing videotape trying to determine how things got started with this.”

Markham, house, fire

The Office of the Fire Marshal (OFM) was called in to probe the circumstances surrounding the fire.

“We’ve had an explosion. The post-explosion fire is fairly significant, and people have been transported to the hospital,” OFM Supervisor Jeff Tebby told CP24.

He said they’ve not been able to conduct a primary or secondary search of the home.

“We’re in the very early phases of making the scene safe so we can start to investigate,” Tebby said, adding that it is too early to know what caused the explosion.

He said OFM will not be going into the home until Monday.

One witness told CP24 that he was first alerted to the incident when he heard what sounded like a cabinet falling down.

“I take a peek outside, and I saw two (people) lying on the sidewalk, and one of the (children) from a neighbour’s walking out, crying,” he said. “That’s when I (knew) something big was going on.”

Teresa Lau, who lives in the neighbourhood, said she was awakened by the explosion that for her sounded like a demolition.

When she looked out to see what happened, Lau said she saw debris blowing towards her house.

A few moments later, she said she saw the six-year-old girl screaming, running across her lawn before collapsing in front of her house.

“I run out there to help her first,” Lau said, who trained with St. John’s Ambulance.

“I felt so bad because the only thing that she could think of is ‘I’m hurt, I’m in pain, and I need to go to the hospital.’ Those were the only repeated words that she kept saying.”

Lau said the girl had shattered glass all over her body. She said the boy and the woman were also severely injured.

“It was really bad like the clothes were stuck on like you cannot make out the difference between a skin and the clothing,” Lau said.

She said she does not know how many people live in the house as the family recently moved into the neighbourhood.

Lau said she heard the woman tell emergency crews that there were two other people in the house.

“The good thing is there are three people that got saved,” Lau said. “I don’t know about the other two. That’s really a tragedy.”