The attack occurred during an all-terrain car racing show in the San Vicente area of the city of Ensenada. Around 2:18 p.m. (2118 GMT) people with long guns got out of a gray van and began shooting at participants at a gas station, according to reports of 911 calls, Reuters reported.
Municipal and state police, the Marines, the Fire Department and Mexican Red Cross, among other agencies arrived at the scene.
Mayor Armando Ayala Robles said state Attorney General Ricardo Ivan Carpio Sanchez commissioned a special group to investigate the shooting.