Authorities said the small fire was sparked by an electrical malfunction about 2:45 p.m.
None of the marijuana plants were burned in the fire, which was extinguished in about 30 minutes.
Police Sgt. Rich Vierra said there is no sign that the 7,000-square-foot building is a working fortune cookie factory, bakery or retail outlet. The sign for Kar Mee Fortune Cookie Factory, however, remains on the building in the 200 block of Seventh Street in the Chinatown district of Oakland.
Police said plants, which ranged from seedlings to 4 feet tall, were being grown in a space of about 1,750 square feet. Inside the building, there is an overpowering smell of marijuana, growing tubs, chemicals, lights and other accessories used for growing marijuana plants, police said.
Police said the person or people who were growing the plants also were pirating electricity to power the lights, ventilation and irrigation systems.
The grower may or may not have been paying for some power but was able to tap into an old line in front of the building, police said.
Police said those who were growing the plants were extremely security conscious, with iron gates on the front of the building and something police described as an "iron cage" protecting the roof and skylights.
Vierra, who worked narcotics for many years, said the
The Kar Mee Fortune Cookie Factory was founded in 1977, but a new owner took over the cookie business in 2007, according to the business's Web site. The phone number listed on the Web site for the cookie factory is disconnected.
An eviction notice on the building shows that the cookie factory was booted out in November 2008. Police said neither the building owner nor the former cookie business owner nor those responsible for the grow operation have been contacted yet.
A woman, who declined to give her name, who lives near the building said she frequently smelled marijuana but always thought it was coming from a different building.