There were 27 passengers in the SUV that struck a semitruck full of gravel, said Judy Cruz, the managing director of the Emergency Room Department at El Centro Regional Medical Center.
She said 14 people were dead on the scene, and another person died shortly after arriving at the hospital. Other passengers are being treated at El Centro Regional Medical Center and at Pioneers Memorial Hospital in nearby Brawley.
"Patients are going through a difficult time as you can imagine," El Centro Regional Medical Center CEO Adolphe Edward said. "This was a major accident and we are taking care of them in the emergency room department."
The Desert Regional Medical Center in Palm Springs is caring for four patients from the crash, hospital director of communications Todd Burke told CNN. Three of the four patients are in the intensive care unit, and all four were flown in directly from the scene to the trauma center.
California Highway Patrol Officer Arturo Platero said the vehicle was moving westbound on Norrish Road near State Route 115 when it traveled "in the direct path" of a big rig truck traveling northbound on 115. The cause of the crash is under investigation.
Video posted on social media that purports to show the crash's aftermath depicts a number of police, ambulance and fire vehicles at the scene. The road appears to be completely shut down as some emergency responders look to be helping the wounded.
A jack-knifed truck, with two trailers attached to it, sits on the road. As the camera pans left, two helicopters can be seen.
CNN has reached out to the individual that posted the video but they did not immediately respond.
The site of the crash is in southeastern California about 10 miles east of El Centro and about 10 miles north of the Mexican border.
CNN's Paul P. Murphy contributed to this report.
