It happened just before 3:30 p.m. on N Sierra Highway near Via Princessa.
The Los Angeles County Fire Department said one person was sent to the hospital in an unknown condition though it's unclear if that person was in the building or driving a vehicle.
Traffic along N Sierra Highway was backed just as rush hour was set to begin. The county fire department said building and safety inspectors responded to the scene to check the building.
This is a developing story. This article will continue to be updated as more information becomes available.