WILLIAMS: A casino-bound charter bus with an invalid license plate drifted off the road and then swerved back, sending it tumbling into a ditch and ejecting passengers as it rolled, police said. Ten people were killed and dozens injured.

The bus flipped over at about Sunday evening on a rural road, throwing some passengers and crushing others before it landed right-side up, California Highway Patrol spokesman Patrick Landreth said.

The bus, which left from Sacramento, crashed 10 miles (16 kilometers) short of its destination, the Colusa Casino Resort. Nobody from the bus was identified; many of the passengers were Laotian.

``It looks like they were going up to the casino to have a goodtime,'' California Highway Patrol Commander Fran Clader said Monday. ``Unfortunately, it resulted in tragedy.'' Clader said 10 people were dead and estimated that 35 others were injured.

Authorities did not say why they think the driver veered off the road.

Firefighters used flashlights and infrared sensors to search the tall grass near the overturned bus Sunday night for more victims, but by early Monday were certain they had accounted for all the victims. The mud-covered bus was pulled from the ditch and was on a large tow truck.

Just before the accident, the bus veered off the two-lane road for about half a mile before the driver ``overcorrected'' and swerved back, Landreth said.

``The roof was collapsed down, the windows were broken out, and the bus was not only rolled over onto its side, it rolled completely over,'' Landreth said. ``It was facing the opposite direction and it was on its wheels.''

Authorities had not determined the name of the charter company early Monday morning.

The bus had ``Greyhound'' marked on its side. But a Greyhound official said it was no longer operated by the company.

``It is not our bus. We sold it more than two years ago,'' said Kim Plaskett, the Greyhound spokeswoman. ``It is an old bus.''

CHP spokesman Robert Kays said the bus had a Texas license plate that was ``not valid.'' He said other registration serial numbers also came up invalid.

``There are still several pieces of this puzzle that's missing, ''Kays said. ``We will find out who owns the bus.''

CHP dispatcher Terry Troth said no other cars appeared to be involved in the crash.

Troth said he did not know the extent of the injuries. He said emergency responders were having trouble communicating with the passengers because many spoke Lao.

Clader said helicopters took victims to several area hospitals.

The crash took place in an area of rice fields and orchards a few miles east of Interstate 5 just north of Williams.

Laura Hennum, a spokeswoman for Enloe Medical Center, said 12victims were admitted to the hospital. She said one died, three were in critical condition and two were in serious condition. Six other patients were being evaluated Sunday night.

``We activated our disaster response center, so we have been calling in additional staff,'' she told the San Francisco Chronicle.