The one-alarm fire at 1433 Grant Ave. was reported at 4 a.m. when Novato police Officer Jennifer Welch smelled smoke in the area, Wargo said. The fire was controlled by 4:40 a.m., Wargo said.
Damage to the structure is estimated at $150,000 and the contents at $100,000.
There were no smoke alarms or a sprinkler system inside the cafe that served breakfast and lunch, Wargo said.
Firefighters escaped serious injury or death when a flashover, a combustion caused by heat buildup, caused an explosion inside the cafe.
Firefighters sensed the temperature change and backed out of the cafe about 40 seconds before the explosion, Wargo said. One firefighter's helmet actually caught fire, Wargo said.
It will likely be several more days before a cause of the fire is determined, Wargo said.