A fire engine crew was returning from a medical call around 2:50 a.m. when crewmembers spotted smoke and found a fire burning at the Tavern at Lark Creek restaurant at 234 Magnolia Ave., according to Larkspur fire Chief Bob Sinnott.
Crews saw heavy smoke coming from the second floor of the Victorian building, according to Sinnott.
Fire personnel quickly upgraded the incident to a second alarm and crews from the Larkspur, Corte Madera, San Rafael, Kentfield, Mill Valley and Ross Valley fire departments were called to assist.
Firefighters were able to control the fire in about 90 minutes after the blaze burned portions of the building's roof, eaves and attic areas, the chief said. The restaurant's dining and kitchen areas sustained significant smoke, heat and water damage, Sinnott said.
The chief said the fire appears to have started near an oven flue exhaust pipe in an area of the building's roof. However, the exact cause of the fire is under investigation.
No injuries were reported.
Damage estimates were not available but Sinnott said the building remains structurally stable and should be ready for repairs and remodeling soon.
The chief credited the firefighters who spotted the blaze for their quick action in locating and attacking the blaze.
"Because few people are awake at this hour, this most likely prevented a delay in receiving a report of the fire and subsequently further damage to the building," he said.
The Tavern at Lark Creek was built in the late 19th Century and served for decades as a home before it was converted into a restaurant in the 1970s, the fire chief said.