Five occupants became trapped, while four others suffered injuries but managed to get out after the vehicle came to a stop on the bridge, the patrol said. The driver escaped uninjured.
Montiel said that the victims were all in their 30s. Authorities said the names of the dead would be released once families have been notified.
The blaze occurred around 10 p.m. on westbound lanes of the bridge, which connects San Mateo and Alameda counties, about 20 miles southeast of San Francisco.
The patrol said that smoke started coming out of the rear of the limo, and the driver pulled over as the vehicle quickly became engulfed in flames. Officers were trying to determine the cause of the blaze, which wasn't the result of an accident.
"We have no idea right now where they were going or where they were coming from," CHP officer Amelia Jack told KGO-TV.
Two of the women who escaped were taken to Stanford Hospital and the two others were taken to Valley Medical Center in San Jose. All four are being treated for smoke inhalation and burns.
The westbound lanes of the bridge were closed as officers investigated the cause of the deadly fire, but the patrol said one lane of traffic reopened early Sunday.