A massive fire at Speeway Fuels Oct. 1 was caused by the spontaneous combustion of an oily substance, officials say. (CBC)

A massive fire at Speedway International in Winnipeg's St. Boniface neighbourhood was an accident caused by the spontaneous combustion of an oily substance, according to fire officials.

The fire broke out Oct. 1 around 5:30 p.m. CT and forced the evacuation of about 100 nearby homes due to heavy, black smoke.

There were no injuries in the fire, which caused an estimated $15 million in damages. The company produced fuel, including methanol-based products, for the auto racing industry.

"It should be noted that spontaneous combustion of materials can occur when a material with a low ignition temperature begins to self-heat," Manitoba's Office of the Fire Commissioner reported Friday. "This self heating occurs through the decay of the material which generates heat to the point of combustion."

Officials included in their note observations about how spontaneous combustion can take place.

They noted the dangers of oily rags.

"The OFC will be working with the Fire Safety Inspection sub-committee to consider whether there should be any changes (or mandated time frames) for inspections of these, or similar types of industrial facilities," the office added. The committee includes a number of representatives from different agencies, including fire departments and municipal officials.

"Municipal involvement is critical because enforcement of the fire code, and responsibility for zoning rests with each municipality," the office said.

The City of Winnipeg responded by saying it is too early to say how it, or the Winnipeg Fire Paramedic Service will be involved in the sub-committee.