The two-alarm fire was reported at 8:56 p.m. Tuesday at Auto Market & Truck, located at 140 San Jose Ave. Firefighters arrived and found the 10,000-square-foot building and three vehicles on fire.
The blaze, which was extinguished in about 30 minutes, caused about $1.5 million in damage, San Jose fire Capt. Chuck Rangel said.
Investigators have determined the blaze was arson-related, but Rangel said he could not yet specify how that was determined.
"We're following some really good leads," he said.
A police officer responding to the scene suffered minor smoke inhalation, but was treated at the scene and released, Rangel said.
A nearby business and a house were initially threatened by the blaze. Three people evacuated from the home were allowed to return once the fire was under control.