A 19-year-old man was being treated for a gunshot wound to the chest after being shot Monday evening near an Oceanside middle school, police said. The teen was shot in front of Cesar Chavez Middle School on Oleander Drive around 6:25 p.m. When police arrived they found the man with a gunshot wound to the right side of his chest, said Oceanside police Sgt. Mark Bussey. Paramedics transported him to a hospital, where he is being treated for injuries not believed to be life-threatening, Bussey said. Investigators located three 9 mm shell casings in the parking lot at the school, and a witness reported seeing someone shooting from the rear passenger seat of an SUV with silver trim. The vehicle was last seen heading east on Oleander Drive. Police believe the shooting was gang-related, Bussey said. Officers canvassed the area and tried to find the vehicle with the assistance of a sheriff’s helicopter Monday night but were unable to locate it.