FAIR OAKS, Calif. » Two vehicles collided head-on in a fiery crash near Sacramento, California, leaving four people dead and two more seriously injured.

The Sacramento Bee reports the crash happened about 1:30 a.m. Friday in Fair Oaks, which is northeast of Sacramento on the north bank of the American River.

CHP officials say 26-year-old David Mazur was driving his 2003 Subaru Outback north on San Juan Avenue when a 1992 Buick LeSabre driving south veered over the centerline and hit his car head-on. Mazur is in serious condition. Tests showed he was not under the influence of alcohol when the crash occurred.

There were five people in the Buick, and three of them burned to death. The car was fully engulfed in flames when authorities arrived on the scene.

A nearby resident pulled the other two people out of the Buick.

One of the two, a young woman, died at the scene. The other woman was taken to a hospital, where authorities say she was in critical condition Friday.

The CHP is investigating the cause of the crash.

"Everything was just tossed around. It’s very difficult for us to investigate," CHP spokesman Officer Chad Hertzell said.

A toxicology test will be conducted on the driver of the Buick to determine if alcohol played a part in the crash, Hertzell said.

Officers said it appears speed played a role. Some of the passengers in the Buick were not wearing seatbelts, according to the CHP.

A CHP official said the agency has spoken with relatives of those in the Buick, but the coroner’s office has not released the names of those who died.