An eye witness described the movement of a bus that crashed and killed eight people on the way to a Colusa County casino Sunday night as erratic as it careened along a country road.

Authorities confirmed this morning that eight people died in the crash near Williams, and the driver has been arrested on a charge of driving under the influence.

The witness, an off-duty sheriff's deputy, saw the bus carrying 43 people swerve back and forth across the road before rolling and spilling many of its passengers into a field.

An off-duty Colusa County Sheriff's deputy was driving south on Lone Star Road when he spotted the bus moving erratically Sunday evening, said Stephen Bell, assistant chief of the CHP's northern division office.

The bus drifted to the right side of the road and back again, and then crossed over the road again and hit the dirt to the left of the roadway, he said.

The bus rolled over once and landed on its wheels. Several passengers were ejected from the bus when it crashed.

The Colusa County Coroner's Office said today it had seven victims of the crash, and an eighth victim was reported by the Butte County Coroner in Chico.

The bus owner, Daniel E. Cobb, 68, of Sacramento, was killed in the crash.

Quintin Joey Watts, 52, of Stockton, is in critical condition in Woodland Memorial Hospital, one of 35 people authorities say were hurt in the crash as the bus was traveling from Sacramento to the Colusa Casino, a gaming establishment in rural Colusa County, near Williams.

Watts was arrested on suspicion of driving under the influence, said CHP Sgt. Brian Donnelly. It is unclear whether he was under the influence of drugs or alcohol, he said.

He will be jailed upon his release from the hospital, he said.

The crash occurred at 6:10 p.m. on Lone Star Road, a two-lane road fronted by a water-filled ditch. The road is a popular shortcut for motorists headed to the casino, and the crash site is about six miles from Williams and four miles from Colusa.

No other vehicles were thought to have been involved, and the accident occurred before darkness fell on the area, which is largely rice fields and farmland.

Watts was arrested based on observations a witness made before the crash, Donnelly said.

"He was driving erratically," he said. "The bus basically veered off the road for no reason."

Watts' driver's license is valid, but the paperwork on the bus is not, Donnelly said.

In addition to Cobb, authorities have identified five other victims, all women from Sacramento: Lou Her, 68, Muang Saephanh, 68, Khou Yang, 67, Meuay Saelee, 74 and Fin Saechae, 64.

Officers combed the crash scene overnight, using infrared equipment in a helicopter flying over the fields and an extensive grid search on foot at daybreak.

CHP officials say they are "reasonably sure" they found everyone who had been on the bus, Bell said.

The CHP has launched a criminal investigation into the crash.

CHP Special Officer Robert B. Kays said at the crash scene early today that the bus had Texas license plates and had an invalid registration. The muddled registration information impeded the CHP in determining the bus' owner before Cobb was identified as the owner.

Cobb owned Beeline Tours, on Franklin Boulevard, and Cobbs Bus Service, a limited liability company on Den Avenue, public records show.

On Thursday, Cobb posted an ad on a free local classified advertising Web site seeking a charter bus driver.

"Charter Bus Driver position available, works is full or part-time. The business is within a 100 mile radius, only duties required is driving," the ad on http://sacramento.kijiji.com states.

Wreckage was cleared from the crash site at 5:35 a.m. today, opening Lone Star Lane, a two-lane road that is a favorite shortcut from Interstate 5 to the casino.

The bus was full of Laotian Hmong heading to Colusa Casino Resort, Sgt. Donnelly said.

About two-thirds of the crash victims had to be rescued from the bus.

Many had cuts, broken bones and internal injuries, he said.

"They were just basically beat up from the wreck itself," he said. "There was a lot of metal debris and glass."

Donnelly said Colusa County is no stranger to bad car crashes, but Sunday's bus crash was horrific.

"It was, by far, the worst I have ever seen," he said.

Don Kennedy, marketing director at Colusa Casino Resort, said the casino was not expecting the bus Sunday.

Casino officials said in a written statement that the bus involved in the crash "was not scheduled to bring guests to our facility."

"The Colusa Casino Resort is stunned and saddened by this tragic bus accident that has resulted in several deaths and serious injuries to people who were coming to our facility," the news release states. "Our prayers and sympathy go out to all of the passengers, their families and anyone else who may have been affected by this accident."

The single-vehicle accident sparked a massive emergency response from Sacramento to Chico, with hospitals, fire departments and other officials racing to the scene of the crash in Colusa County.

The Bee's Andy Furillo and Sam Stanton contributed to this report.

Call The Bee's Niesha Lofing, (916) 321-1270.