An entire strip mall was evacuated Sunday due to an "off-the-charts" natural gas leak in its mechanical room in a northeast Edmonton neighbourhood Sunday morning.

Fire crews were called to a mall in the Belmont neighbourhood just off Victoria Trail after reports of a natural-gas smell in two businesses.

When they arrived, they found the gas leak and some burnt paper and charred walls, which Edmonton Fire Rescue Service's Len Mushtuk said could mean there was a small explosion inside the mechanical room.

Crews investigating backroom, gas tanks now sitting outside. District fire chief says power and gas to building cut <a href="https://t.co/MsXlrTs20g">pic.twitter.com/MsXlrTs20g</a> —@roberta__bell

The gas seeped into multiple businesses, including Sobeys and a liquor store. A nearby McDonald's was also evacuated as a precaution.

"The gas levels were off the charts," district chief Len Mushtuk told reporters Sunday. "Natural gas had been leaking into the buildings for some time."

Crews evacuated all open businesses as a precaution while they worked to shut down the leak. They also were forced to break into businesses that were not open to ventilate them. No one was injured.

Mushtuk said he expects crews to be on-scene for at least a few hours, and he's not sure whether the mall will reopen Sunday.

'Building is filled with gas'

Thomas Baumann, a manager at the Spirits of Belmont liquor store, was walking to work at around 9:30 a.m. when he smelled natural gas outside the building.

Fire crews were forced to break into some businesses, as a few of them were closed Sunday. (Roberta Bell/CBC)

When he walked into the store, he says the smell was a lot stronger. "The whole building is filled with gas," he told CBC News. He immediately phoned Epcor and the police.

He said two others working at Subway were also outside and called the building manager.

Baumann walked into the mechanical room with the building manager and saw two propane tanks open. "And somebody tampered with the natural gas line," he said.

Mushtuk said it's too early to speculate whether the line was tampered with, but said investigators will determine that in the coming days.

'Better than an explosion'

Crews were able to contain the gas leak with minimal issues — but Mushtuk said it could have been a lot worse.

"If there was an ignition source and the gas levels were just right with the mixtures of oxygen, the potential for disaster could have been pretty high," he said.

The area was cordoned off for a few hours. It's not clear if the mall will reopen Sunday. (Roberta Bell/CBC)

Fire crews had to break down doors as a few of the businesses weren't open, but Baumann said that's better than the alternative.

"I guess it's better than an explosion," he said.