San Francisco, March 3: At least 13 people were killed in a traffic collision near the US-Mexico border in Southern California, according to the police.

California Highway Patrol Chief Omar Watson said at a press conference on Tuesday afternoon that 12 people were killed at the scene just outside of Holtville, California, which is about 17.7 km north of the US-Mexico border, and another died after arriving at the hospital, reports Xinhua news agency.

Hospital sources said earlier that at least 15 people were killed in the accident.

Judy Cruz, the El Centro Regional Medical Center's emergency department director, told the media that six others are being treated.

She added that at least five others were sent to other medical centers for treatment.

"The patients are, of course, going through a little bit of a difficult time, as you can imagine," said Adolf Edwards, Chief Executive Officer of Central Regional Medical Center.

"This was a major accident and we are taking care of them in the emergency room department."

The NBC Palm Spring news channel said the accident occurred at 6.16 a.m. on Tuesday in a place about 10 miles east of El Centro, the largest city in Imperial County, California.

A red Ford SUV running westbound travelled "in the direct path" of a big rig truck travelling northbound at an intersection in the rural area, both police and doctors confirmed, but they provided different information of the number of people in the SUV.

"Twenty-seven passengers were believed in the SUV" when the accident occurred, Cruz said.

But Watson said the number was 25.

Macario Mora, a spokesman for Customs and Border Protection in Yuma and El Centro, said the immigration status of those in the SUV was unknown and being investigated.

"It was an unusual number of people in an SUV, but we don't know who they were," Mora said, adding that they could have been farm workers.

13 dead in car crash near US-Mexico border