The other three fatalities of the 9:35 p.m. Sunday collision were three brothers, the Los Angeles Times reported.
Fontana police Sgt. Billy Green said a sport utility vehicle ran a red light, hit two other cars and rammed a utility pole. In one car was a 40-year-old Fontana woman whose 11-year-old son, Noah Ferrer, died Monday in surgery. The woman's name and condition were not reported.
Two men in the SUV, a 35-year-old from Rancho Cucamonga and his 39-year-old brother from Bloomington were dead at the scene and their 37-year-old brother from Fontana died at a hospital, Deputy Mark Johnson of the San Bernadino County coroner's office said.
Green said while the cause of the crash was being investigated, police found beer cans and firearms in the brothers' SUV.