An explosive fire at an apartment building in Moncton, N.B., with businesses on the main floor has forced five people out of their home.

The Canadian Red Cross says the fire was reported around 11 p.m. Sunday at a building on George Street.

Building owner Hossein Barrar was watching from the street. He thought the fire could have turned into a terrible tragedy when it exploded.

“It caught everybody by surprise,” he said. “As much as the firefighters on the roof on the ladder with those on the ground helping them out.”

“We were surprised by a backdraft,” said Chief Eric Arsenault of the Moncton Fire Department. “There were no signs prior to this even occurring.

Twenty firefighters rushed to the scene. Despite the backdraft, not a single one was injured.

“We were extremely lucky,” said Arsenault. “I wish I could explain why nobody got hurt. Good graces, it just so happened that the three firefighters were able to come down without a scratch.”

The fire damaged the building, which has a health food store and sushi restaurant on the ground floor and three upstairs apartments.

Fighting the fire was a challenge from the start. The building was old and had been renovated a number of times, making it difficult to find where it started.

“They couldn't get the fire, it was between the roof and siding and it’s hard to get in,” said Barrar.

Barrar says he'd eventually like to rebuild his shop in the same location.

“This is the best of the worst,” he said. “At least nobody got hurt.”

The Red Cross says volunteers arranged emergency lodging, food and clothing for a man from one apartment.

Four people in the other units were staying with family.

It’s not known how the fire started. Investigators say they may never know.

With files from CTV Atlantic’s Nick Moore and The Canadian Press.