The teens, ages 12, 14 and 17, were taken to a local hospital with non-life threatening injuries.
Police are searching for the suspect, 48-year-old Raul Izarraras Ramirez, who was described as a Hispanic male, 5 feet 7 inches tall and 180 pounds.
Authorities said he is considered armed and dangerous. The motive for the shooting remained under investigation.
Anyone with information was urged to call the San Bernardino Police Department at (909) 384-5745.