California accident investigators on Sunday were attempting to determine why the driver of a truck competing in a popular California off-road race lost control and hurtled into a crowd of spectators the night before, killing eight people and injuring more than two dozens others.

Six victims died at the scene, two died at nearby hospitals and at least seven people were seriously injured amid the screaming and chaos in the darkness, according to the California Highway Patrol.

The driver and his passenger weren't hurt. Seventeen additional spectators received less-severe injuries. Most of the dead were in their 20s.

The crash occurred barely 15 minutes into a 200-mile race that started near Lake Lucerne, in the Southern California desert. The driver apparently lost control going over a ridge and his modified 2004 Ford Ranger tumbled and landed upside-down in a portion of the crowd lining the course, according to a spokesman for the highway patrol.

The driver, identified as Brett Michael Sloppy, 28 years old, of San Marcos, Calif., and an unidentified passenger weren't injured. The two were whisked away for their own protection, according to CHP spokesman Joaquin Zubieta, but were later released without any charges filed.

The spokesman said the responding officers determined that "alcohol wasn't involved" in the crash and the driver was released after questioning. Mr. Sloppy couldn't be reached for comment.

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