Lisa Vanderpump's Famous Restaurant Catches Fire

Lisa Vanderpump's restaurant PUMP had some surprise patrons Friday morning -- LA County firefighters who rushed in to put down a kitchen fire ... TMZ has learned.

Fire department sources tell us they arrived around 11 AM and quickly put down a small smoldering electrical fire that was contained within a wall. It caused no injuries or major damage.

'RHOBH' and "Vanderpump Rules" fans know PUMP well, and as a result ... it's also become a big tourist stop. We're told they'll be open for biz tonight ... if you can get a reservation.