A family on vacation in California was involved in an accident that killed 4 and injured 6

Police said visiting families from Mexico were involved in a head-on collision on a California freeway that killed four and injured six others.

Two vehicles that appeared to be a large SUV and a midsize sedan crashed on Highway 12 in Rio Vista shortly after 8:00 PM, Sgt. Rex Hawkins told NBC News.

He said there were fatalities in both vehicles involved in the accident.

The four people who died were presumed dead at the scene, while all six injured were taken to hospitals, the Rio Vista Fire Department, which responded to the incident, said in a statement.

Although authorities have not disclosed the names and ages of those killed or the condition of most of those injured, Rio Vista police chief Jon Mazer told NBC Bay Area that one person is doing “reasonably well.”

Rio Vista is more than 50 miles northeast of Oakland.

“Speaking from just one person at the hospital, I know they were on family vacation from Mexico,” he said. β€œThe second car, I would say it’s young people. I don’t know their age, but I would estimate that we are dealing with young 20-year-olds ”.

The fire department has warned that an investigation into the accident will affect traffic in the area.

He also said his handling of non-emergency calls could potentially be slightly delayed due to efforts to help transport patients to hospitals.

The cause of the crash remains under investigation.

Kurt Chirbas is the senior editor of NBC News, based in New York.

Chantal Da Silva is the latest news editor for NBC News Digital, based in London.