SOUTH PORTLAND – A fire that ravaged a building at Southern Maine Technical College was accidental, investigators said Wednesday.

Investigators from the state Fire Marshal’s Office reported that the most likely cause of the fire was materials that had been stored too close to a steam-heating register in the building’s basement.

The boxes and paper had been there for about 10 years, said Stephen McCausland, spokesman for the Maine Public Safety Department.

No one was hurt in the three-alarm blaze at Preble Hall. The building housed classrooms for the South Portland school’s computer programs. Damage was estimated at between $1 million and $1.5 million.