The provincial fire marshal said a combination oil and wood-burning furnace is to blame for an explosion that rocked a Waterville, N.S. home and sent six people to hospital early Tuesday.

The explosion was originally thought to be gas related, but Harold Pothier has ruled that out after assessing the site. He said it appears the furnace overheated and ruptured, causing an explosion at the single-storey home on Porter Lane.

Smoke was pouring out of the home when firefighters arrived after 1 a.m., but Waterville Fire Chief Wayne Johnstone said there was no fire.

"There was total destruction in the house," said Johnstone. "It shook the house big time."

Three children and three adults were inside the home at the time. They were all taken to hospital, but five have since been released.

Malcolm Spencer, a volunteer firefighter who lives a few doors down, was first on the scene.

“(I called out) ‘Donnie, Donnie, anybody, speak to me,’ and I didn't get a response for quite some time,” Spencer recalled.

“I proceeded to work my way through the darkness and that, and got downstairs and there were was two little children in there plus two adults,” he said.

One by one, Spencer got them out of the house and into his truck.

By then, his fire chief had arrived, along with other members of the Waterville FireDepartment.

According to the Nova Scotia fire marshal, the explosion lifted the home right off its foundation.

The damage visible from outside the home includes a door and some windows that have been blown out of their frames.

Spencer said it was a hellish scene when he arrived.

“Something I’ve never seen in my life, and I’ve been in the fire department forever,” Spencer said.

“It’s unbelievable that anybody ever walked out of it,” he said.

The RCMP said a 63-year-old man remains in hospital with non-life-threatening injuries.

Gloria Porter says the man is the homeowner and her nephew, Donald Eisnor, who is being kept in hospital so doctors can monitor his heart.

“It’s a sad, sad mess, I’ll tell you,” she said.

The other people in the house at the time were Eisnor’s wife, daughter and three grandchildren, she said.

Porter is now looking after the family’s dog, which her nephew brought over to the place shortly after the explosion, she said.

Firefighters and the provincial fire marshall were back at the destroyed house on Tuesday afternoon.

“We understand they were utilizing a heating appliance and when that heating appliance would have kicked in sometime during the night, shortly after 1 a.m., the explosion occurred,” Pothier said.

In a statement released Tuesday afternoon, Pothier said the timing was fortunate.

“Thankfully, the occupants were sleeping, and therefore laying down, which may have saved their lives,” he said.

With files from CTV Atlantic's Jacqueline Foster and The Canadian Press