A fire last week at Cavallero Heating & Air Condition has been ruled arson, authorities said Wednesday.
"There was definitely an incendiary (component) to the fire," said Steve Mihelic, assistant battalion chief for the Carson City Fire Department. "It was obviously arson."
Mihelic said the fire began in the northeast corner of the downstairs by someone who had access to the interior of the building.
He said detectives from the Carson City Sheriff's Department are interviewing people to try to determine a suspect.
"We've figured out what happened; now we are finding out who did it," he said. "We are developing suspects and will pursue those as long as the investigation takes us there."
Drivers on Highway 50 reported the blaze about 4:48 a.m. Friday and the first firefighting crew arrived minutes later.
The east end of the building, at 5441 Highway 50 East, was gutted before firefighters could cut off the fire at a stairwell. The remaining 70 percent of the 24-year-old building, untouched by fire, suffered severe smoke damage.
The business offices and roof were severely damaged, but inventory loss was minimal. Owners Sue and Ken Cavallero were able to reopen the next day.
Fire damage is estimated at $350,000 and cost the city $10,000 to fight.