Officers responding to a report of individuals walking on San Bruno Avenue near Fourth Avenue at about 1:45 a.m. today observed a vehicle with several occupants leaving the scene.
An officer attempted to stop the vehicle near Belle Air Elementary School, and, although the vehicle stopped, its occupants fled.
As the officer chased one of the suspects, the person turned and fired a handgun at the officer. The officer, unharmed, returned fire as the suspect continued to flee.
Police said it was unknown if that suspect was struck.
After establishing a perimeter, police located and took into custody two of the suspects, whose names have not been released.
Police described the third suspect as a Hispanic man in his early 20s who is 5 feet 11 inches tall, weighs 155 pounds and was last seen wearing all dark clothing.
Anyone with information is asked to contact San Bruno police at (650) 616-7100.