WILLIAMS, Calif. -- The driver of a bus involved in a Colusa County crash that killed eight people and injured dozens of others is accused of driving under the influence, the California Highway Patrol said Monday.

The 52-year-old driver, Quintin J. Watts, was arrested at Woodland Memorial Hospital, where remained in critical condition as of Monday, officials said.

CHP Sgt. Pat Lundreth said Watts was on medication. Stephen Bell of the CHP did not specify if the DUI charge against Watts is related to drugs or alcohol.

"It could be a combination of both," Bell said during a news conference in Williams.

The 1993 MCI bus, which was heading to Colusa Casino from Sacramento, was carrying 43 people at the time of the wreck. Up to a dozen passengers were thrown from the bus as it violently flipped before coming to rest in waist-deep mud at the edge of a rice field. Authorities said 35 people were injured. Police earlier said 10 people died, but revised the number to eight.

Crash victims remained at UC Davis Medical Center and several other hospitals around the region after the wreck, which occurred at about 6:15 p.m. Sunday near Williams along Lone Star Road close to Abel Road.

An off-duty Colusa County sheriff's deputy who witnessed wreck described Watts' driving as "erratic" prior to the crash, Bell added. The bus went off the shoulder of the road, overcorrected and rolled one time.

"(The deputy) observed numerous people get ejected from that bus as it was flipping," said Bob Kays of the CHP.

Bell said many of the crash victims were Asian and in their 40s and 50s. He said a Lao-speaking interpreter was brought in to interview them.

Meanwhile, the CHP said a preliminary investigation has found the bus belongs to Cobb's Tours of Sacramento. It is owned by Daniel Cobb.

The California Department of Motor Vehicles said Watts has a valid commercial driver's license.

Watts' license was suspended in 2006, the DMV said, but it was reinstated in January of this year. Watts lives is a Stockton resident.

While the bus had some markings suggesting it belonged to Greyhound, the company said the bus was sold two years ago.

The bus has a Texas license plate, but is not registered. A Department of Transportation number on the bus did not turn up any current records.

Greyhound spokeswoman Kim Plaskett said the bus had no seat belts.

Lone Star Road reopened early Monday, about 10 hours after the crash. The bus was pulled back onto the road at about 4 a.m.

The crumpled bus was taken to an impound yard in Williams, where officers were starting to inspect the wreckage. An investigation involves officials from the CHP, federal Department of Transportation and the state Public Utilities Commission.

At the crash site, investigators on Monday morning could be seen taking a close look at the muddy spot where the bus came to rest.

Rescuers from several cities converged on the crash site on Sunday evening. Ambulances rushed to the area and medical helicopters ferried the injured away.

Several hospitals received victims from the crash, including:

UC Davis Medical Center in Sacramento

Woodland Memorial Hospital in Woodland

Enloe Medical Center in Chico

Santa Rosa Memorial Hospital

Sutter Roseville Medical Center

St. Elizabeth Community Hospital in Red Bluff

Oroville Hospital

Mercy Medical Center in Redding

Six of the injured were brought to UC Davis Medical Center. At one point on Sunday night, medical helicopters had to wait for a turn to land at the hospital to drop off patients.

Some family members also showed up at the hospital hoping to learn about the status of their loved ones.

Pa Vang came to the hospital looking for her parents, who often take a bus to the casino.

"Hopefully, one of them might be Mom and Dad, but we don't know yet," she said.

Colusa Casino said staff members were "stunned and saddened" by the crash.

"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 casino said in a prepared statement.