EDMONTON - Fire officials have charged a Calgary exterminator for starting a $3.5 million fire while trying to quell an infestation of bedbugs in a downtown Edmonton condo last July.

On Monday, Edmonton Fire Rescue officially charged Bed Bugs Task Force Ltd. under the Alberta Fire Code and fined the out of town company $10,000 in a move officials are calling groundbreaking.

"It's pretty unusual for Edmonton Fire to pursue a case like this," said deputy fire chief Russell Croome Tuesday, adding most fire-related charges are handled by the police. "I don't recall any other case when fire code charges were laid as a result of a fire."

The pest-control company was working on the building July 12, 2011, when they sparked a blaze that injured five people, including three children, and displaced 50 others.

Bed Bugs Task Force Ltd. plead guilty Monday to one count of "conducting hot works in an area not free of combustible and flammable contents" under the Alberta Fire Code.

Investigators at the time said the fire was sparked by a propane-fuelled heater the company was using to exterminate an infestation of bedbugs on the fourth floor of the complex.

Croome revealed Tuesday the company's de-bugging process is outdated and does not meet all of the Alberta Fire code regulations.

"In Edmonton, we're not aware of any other companies that use that method. They use a more intrinsically safe method," he said, adding property owners should do their homework before hiring a pest-control company.

"There are some safer methods. You could ask them if they have met the fire code requirements."

The massive fire also damaged a neighbouring mosque and an apartment building.