The fire, which has gutted out over dozen homes since it broke out at around 6 pm on Thursday, Sep 9 evening (local time), continues to rage on.
An explosion was heard before the fire broke out. Local media reports also suggest that there might have been successive explosions due to the scores of cars parked in the locality.
The initial speculation that the fire was caused due to plane crash has been refuted and the possibility of a ruptured gas pipeline causing the blaze is being investigated into.
The San Bruno suburb is located not very far from San Francisco International Airport. With several witnesses seeing a large ball of fire before the fire broke out, the possibility of a plane crash emerged.
However, Federal Aviation Administration (FAA) spokesman Ian Gregor said "At this time we don't think it's a plane."
Fire fighting operations are on.
Visuals of the fire shows several buildings engulfed in flames as a black plume of smoke arising from the suburbs.