An extermination company is on the hook for $10,000 after pleading guilty to starting a $3.5-million fire at a downtown Edmonton condo building last summer.

Fire damaged the roof of the 50-unit Royal Scot Condo building. (CBC)

Bed Bugs Task Force Ltd. was charged under the Alberta Fire Code in connection to the Royal Scot Condominium fire on July 12, 2011.

The company was fined $10,000.

Four people were hurt in the fire which began on the top floor of the three-storey building at 92nd Street and 105th Avenue.

Two adults and two children were taken to hospital with severe smoke inhalation with one adult and one child listed in critical condition.

Two firefighters were also hurt from falling debris.

Bed Bug Task Force was exterminating bed bugs using a propane heater in a suite on the top floor of the 66-unit building.

Investigation revealed several fire code contraventions which likely contributed to the ignition and the rapid spread of the fire, said Russell Croome, Deputy Fire Chief of Public Safety.

The company was charged with four violations of the Alberta Fire Code.

On Monday Bed Bug Task Force pleaded guilty to one count of "conducting hot works in an area not free of combustible and flammable contents."

The Provincial Court of Alberta accepted a joint submission from the city prosecutor and defence counsel and imposed a $10,000 fine with the remaining counts withdrawn.

“The Royal Scot fire was preventable, posing needless risk to the public and emergency responders,” said Croome in a press release.

“We rarely lay charges but took this action to hold those responsible accountable for failing to take safety precautions.”