The blaze was reported at 12:30 p.m. at 691 San Carlos St., San Jose fire Capt. Chuck Rangel said. Firefighters declared the flames under control by about 2:40 p.m.
One firefighter suffered a muscle strain and was taken to a hospital for treatment, according to Rangel.
The fire escalated to four alarms due to the temperature in San Jose this afternoon, which reached 91 degrees when the blaze was burning, Rangel said.
No one appears to have been in the building during the fire, he said.
The cause remains under investigation.