IRVINE, California (AP) — An investigation is continuing into the fiery freeway crash of a car driven by an unlicensed teenager in Southern California that left five youths dead.

Investigators will inspect the 1995 BMW for signs of mechanical failure that might have contributed to the crash early Saturday in Orange County.

California Highway Patrol Officer Florentine Olivares said Sunday that skid marks on the freeway and the distance the car travelled after hitting a guardrail on Interstate 5 in Irvine suggest speed possibly played a role.

A 16-year-old unlicensed driver was the lone survivor of the crash.

The crash was one of two that happened just hours apart in Southern California that killed 10 people, including three members of the same teen soccer team and four recent graduates of the same high school.

In one, a 16-year-old unlicensed driver was the lone survivor of the crash of a BMW sedan at 2:15 am Saturday. Authorities said the car was carrying six teens returning from the Knott’s Berry Farm amusement park in Buena Park.

The victims included two 14-year-olds boys and a 15-year-old boy, all from Orange County, California Highway Patrol Officer Florentino Olivera said.

Authorities had not released the names of the teens, but the three boys all played for the same soccer team, the Los Angeles Times reported.

They had failed to show up for their 8:00 am game for the elite players of the Mission Viejo Soccer Club. Coach Billy McNicol said he got a call afterward from a family member that all three had been killed.

“We are devastated. Just devastated,” he told the paper.

The car flew off Interstate 5 in Irvine, crashed and caught fire, killing the three boys and two teenage girls, Orange County Fire Authority Capt. Steve Concialdi said. The white sedan was flattened on top and covered with burn marks as it was towed from the scene.

Both girls and one of the boys killed were not wearing a seat belt, the California Highway Patrol said.

Five more people were killed about five hours earlier on Friday night, when three vehicles collided on an isolated two-lane road on the edge of Chino, a city east of Los Angeles in San Bernardino County. Authorities were working to identify the dead and determine the cause Saturday afternoon, police spokeswoman Monica Gutierrez said.

The lone survivor of the three-vehicle crash — the driver of a Honda Civic — was released from the hospital, Gutierrez said. The dead included four in a Chevy truck and one in a Honda Accord.

The victims in the truck included 19-year-old Andrew Anthony Deleon, 18-year-old Nathan Dominguez and two other friends, all recent graduates from the same high school, Dominguez’s uncle Anthony Vasquez and coroner’s officials said.

Vasquez told the Riverside Press-Enterprise that Dominguez, who lives with him, had been scheduled to start a new job at a grocery store Saturday, and he had grown concerned when he didn’t return home before getting the news in the morning.

Vasquez said his nephew was an outgoing and big-hearted teen who “always thought about others before himself.”

The victim from the Accord was Luis Ayala Mendoza, 47, of Corona, the coroner said in a statement.

The 16-year-old driver in the single-vehicle crash was in serious condition with a head injury after undergoing surgery at Mission Hospital, officials said.

There was no record of him having a licence, Olivera said.

Authorities had not filed charges because investigators were still talking to parents and the crash’s cause was not yet clear, Olivera said.

“They are so distraught it is taking time,” he said.