Both drivers apparently were unable to take any evasive action and the vehicles struck head-on in the eastbound lane, according to Highway Patrol Officer Larry Matthews.
Castro's vehicle rolled, ejecting and killing him. His wife, Raquel Jimenez Castro, 40, suffered major injuries and was taken to Palo Verde Community Hospital in Blythe. Information on her condition will not be available from hospital staff until Monday morning, according to an emergency room staffer.
Socorro Magaña Castro, 57, of Holtville died en route to the Palo Verde hospital.
Anthony Castro Jimenez, 7, and his brother David Castro Jimenez, 8, both of Holtville, suffered major injuries and were air-lifted to Children's Hospital in San Diego.
Information on Anthony and David's relationship to the others in the vehicle they were in was unavailable.
A nursing supervisor at Children's said Saturday afternoon that Anthony and David were in critical condition and breathing with the aid of ventilators.
Flores also died in the crash, as did one of his passengers, Juan Luis Villavicencio, 6, of Calipatria.
Juan's brother Arthur Steven Villavicencio, 2, of Calipatria suffered major injuries and was flown to Children's Hospital, according to the Highway Patrol. Arthur was secured in a child seat at the time of the crash. The nursing supervisor at Children's said Arthur was in critical condition and breathing with the aid of a ventilator Saturday afternoon.
Highway Patrol officials reported John Paul Flores was the uncle of Juan and Arthur. The car Flores was driving was registered to the Juan and Arthur's mother, Veronica Flores of Blythe, who was not in the vehicle at the time of the accident.
The only person in the crash to escape relatively unscathed was Luis David Delgadillo, 2, who lived with Socorro Castro, according to the Highway Patrol.
Some fragments of glass were embedded in Luis' eye but he was walking around after emergency crews arrived, Matthews said.
"He's the only success story of the group. He was in a car seat. He got some pieces of glass in his eye, but he's going to be fine. That child seat really saved him," Matthews said.
Luis was seated in the bench seat behind the passenger seat in the sport-utility vehicle at the time of the crash, Matthews said.
All of the occupants in the sport-utility vehicle were wearing seat belts. Emergency crews could not determine whether the occupants in Flores' vehicle were wearing seat belts.
Staff Writer Marcy Misner can be reached at 337-3441.