SAN FRANCISCO – Authorities are investigating whether a faulty steering wheel caused a California raceway crash that killed two people, including the young cousin of the teenage driver, officials said Monday.

The Yuba County Sheriff’s Department is looking into witness reports that the detachable steering wheel came off just before 17-year-old Chase Johnson’s car careened off the dirt track and crashed into pit row Saturday evening, Undersheriff Jerry Read said.

“It’s shaping up to look like a mechanical failure, but there’s still work to be done,” Read said about.

Race car owner Dale Wondergem, 68, and Marcus Johnson, 14, were killed by the collision at Marysville Raceway Park, about 40 miles north of Sacramento, officials said.

The accident occurred when Chase Johnson and several other drivers were doing warm-up laps on opening day of the California Sprint Car Civil War Series.

No one else was injured in the crash, and spectators were never in jeopardy, according to the sheriff’s department.

Marcus Johnson’s father, Rob Johnson, said his nephew Chase told him the wheel detached from the steering column as he was heading into a corner at about 90 mph, according to KTVU-TV.

The car hit a sloped wall, launched into the air and crashed about 150 feet from the track, striking his son.

Johnson said the car was new, so he believes something in the steering wheel’s quick-release mechanism failed.

“He had no control of the car,” Johnson told KTVU-TV. “I don’t know how it could come off. He always double-checked it just to make sure it was down tight. He wasn’t careless.”

Rob Johnson, who lives in Santa Rosa, said the cousins were close friends, and Marcus had been helping Chase at races for three years.

“The two of them were just peas in a pod. They’d do everything together and enjoy every minute of life together,” Johnson said.

Friends and family gathered at Marcus Johnson’s Santa Rosa middle school on Sunday evening, where they remembered the eighth-grader as a passionate basketball player who loved racing cars.

Almost all race cars have detachable steering wheels that drivers must take off with a quick-release mechanism each time they get in and out of the cockpit.

It’s extremely rare for them to come off by accident, said Ron Lingron, the track announcer at Petaluma Speedway who is a friend of the Johnson family.

“When the steering wheel comes off, you have no control over a car going 90 miles per hour,” Lingron said.

Wondergem owned one of the race cars at the track Saturday, but not the one involved in the crash, Read said.