SAN DIEGO — A rollover crash in an open area in San Marcos left one person dead Sunday morning, a sheriff's deputy said.

It happened in a hilly area west of North Twin Oaks Valley Road and north of Bel Esprit Circle, in an area where a neighborhood of single-family homes abuts open chaparral.

It wasn't clear how the single vehicle involved in the accident ended up in the area it was found in, San Diego sheriff's Lt. Chris May said -- it may have been driving off-road, or could have somehow come off a nearby street or driveway, although it appears most of the open area is uphill from nearby roadways.

A passenger in the Chevrolet truck involved in the crash called 911 just before 8 a.m. and told dispatchers the driver of the pickup was trapped inside the overturned vehicle, San Diego sheriff's Sgt. Nicholas Maryn said.

The man was unable to give dispatchers an exact location for the crash scene at the time, Maryn said. Firefighters and paramedics were able to locate the vehicle once they got to the area.

"Due to its remote location, emergency units utilized the hiking trails to access the heavily damaged Chevrolet and the injured vehicle occupants," Maryn said.

All four occupants of the truck, including the driver, were taken to Palomar Medical Center. The driver, a 25-year-old man, died of his injuries at the hospital, Maryn said.

The rest of the people in the pickup were all men aged 25 to 26, and all had moderate but non-life-threatening injuries, the deputy said.

Alcohol was a suspected factor in the crash, according to Maryn.