The fire Saturday at Sudbury Truck and Trailer caused about $10 million in damage, says the Fire Marshal's Office.
Investigator James Allen said Tuesday no cause has been determined as yet, but they know where the blaze began.
"The origin of the fire was in the middle south west section of that building,” Allen said. “Right now, we're looking at potential causes within that area."
Residents around Sudbury Truck and Trailer – located on Whissell Avenue -- were evacuated Saturday, either to a nearby school or to the homes of family and friends. The Red Cross was called in to help with the response.
Five stations responded to the fire, including eight trucks and 36 firefighters.
Allen said he was still collecting information on how the fire started.
"It is a truck and trailer facility, so there lots of tools, lots of acetylene torches and other things inside that area," he said. "We're just collecting some paperwork, some witness statements. Once I have that all done, I'll have enough to sit down and write a report."
There were no injuries as a result of the fire, but residents reported ash rained down across the Flour Mill. The age of the building played a role, Allen said.
"It's an older building, older construction, so you had a wood roof with tar,” he said. “So a lot of that tar and pieces of insulation, with the wind, once you get the heat it will rise and travel a fair distance.
"But that stuff dissipates in the air after awhile."
