At least 10 people were seriously injured Monday after an explosion destroyed one home, damaged several others and left part of the roof from the house that blew up in a yard across the street.

The fire department said the force of the explosion in northeastern Calgary created "a large debris field" and several fires. A tangle of what appeared to be charred beams, pink insulation and splintered wood could be seen where the house once stood.

Homes on either side were charred and one had a shattered window. A tree in front had a piece of plywood and other debris stuck in it.

Many of the injured were believed to have been inside the single-family home when it blew up and were sent to various hospitals in the city, the department said.

"Fire crews have been unable to access the source home at this time to search for any more patients due to structural instability," it said in a news release.

Battalion Chief Paul Frederick said late Monday afternoon that crews were still on scene putting out hot spots but hadn't yet been able to search the basement.

"We believe everyone is accounted for," he said.

Adam Loria, a spokesman for Calgary Emergency Medical Services, said the injured people sent to hospital are all adults.

He said six were in life-threatening condition and four received serious injuries.

"It was quite the group effort, not only with EMS, to ensure all patients were cared for and transported in a timely fashion, but as well with our first responder partners Calgary police and Calgary fire," Loria said.

Several neighbours also ran out to help before emergency crews arrived.

"Once the fire department got here, they cleared it out," said Lee McIntyre, who ran outside with his roommate as soon as they heard the explosion.

"A lot of the neighbours were out here trying to help out as much as they can, bringing water, bringing blankets and everything else trying to help everyone out."

McIntyre said his roommate and a couple others helped the people who lived in the house that exploded, while he tried to get to the woman who lived right next door.

"I was in my housecoat trying to kick in the door next door to get the lady out," he said.

The fire department, he said, ended up getting her out through a window. He didn't know whether she was injured, but he said many people in the main house were badly burned.

"The one guy was really bad," said McIntyre. "A lot of them had burns on their faces and their arms."

Another neighbour, who asked not to be named, said she was among those who helped.

"We heard the explosion," she said. "I poked my head out to make sure they were OK, so I put some shoes on and ran out. It's kind of a blur, but there was already one or two people helping pull some people out of the basement.

"It was just a mess and there was fire coming out."

The woman said she took care of a man who couldn't make it past the middle of the road in front of the house.

"He was very badly injured," she said.

"His arms, his hands, his feet and leg — everything, everything was peeling off."

Ryan Richardson said his parents, Brian and Judy, brought five men who escaped out the back of the house into their garage across the back alley.

"They were the first people to attend to them, basically," he said. "They were worried about putting things on them because of how badly they were burned."

Other neighbours said they and their families felt the explosion as far as a few blocks away.

Bobbie Puttick, who lives eight houses down from the explosion, said it happened after he left for work, but his children were home at the time.

"They felt the house rock and they came out and took a video right away," he said.

"It's nuts to see the house gone. And to see the roof on the other across the street in the neighbour's yard."

The video shows his children running down the street, which is covered in broken trees and pieces of lumber.

"I think a house just blew up," one of them can be heard saying as they run.

As they get closer, the shaky video shows the house in flames.

Lorna Lammers said she heard the explosion from three blocks away.

"I was sitting at my kitchen table and I heard 'kaboom' and I thought something like a vehicle or something had run into my house or my garage," she said.

Lammers said she and her neighbours headed outside to see what had happened and she saw black smoke billowing into the sky. She said there was a lot of debris, including a mattress on the roof of a house.

Lammers said she had previously spoken to some men who lived in the home while walking her dog.

Power to the area was out for about eight hours and crews worked to clamp the natural gas line.

The fire battalion chief said investigators were still working Monday to determine the cause of the explosion, but he noted some neighbours reported smelling gas in the area.

This report by The Canadian Press was first published on March 27, 2023.

— With files from Bill Graveland in Calgary and Emily Blake in Yellowknife