Updated

Prosecutors are considering criminal charges against the driver of a tour bus that careened off a Utah highway, killing three Japanese tourists. Eleven other members of the tour group were injured, with seven of them in critical condition late Tuesday.

The Utah Highway Patrol said it would not identify the driver, a 26-year-old Japanese man, because he was under investigation. Names of most passengers were released.

Iron County Attorney Scott Garrett is screening the case for possible charges, Trooper Todd Johnson said. Garrett didn't immediately return a message from The Associated Press.

Investigators blamed driver error for the rollover crash Monday evening on a straight section of Interstate 15, about four miles north of Cedar City.

"From all indications, the driver was not focussed or paying attention on his driving. He was possibly drowsy at the time, and that's when he went off the left side of the road and rolled it," said Utah Highway Patrol Sgt. Ted Tingey.

The van-sized bus ended up in a mangled heap on its top, wheels up, just off the highway. The passengers' luggage and other debris was scattered across the weedy median.

Three of the passengers were found dead at the scene. "I could tell," said Kristi Christensen, a Salt Lake city nurse who was on the highway, told The Salt Lake Tribune. "I got out and started CPR on one person, but they were gone. I feel awful."

Another seven passengers were flown in critical condition to hospitals in the Salt Lake City area, 250 miles away, including a 14-year girl from Osaka, Japan, according to authorities and a tour company.

Four additional passengers were left in serious or stable condition, and some of them have been released from a Cedar City hospital.

The bus driver also was treated for minor injuries and released.

The injured were first taken to Valley View Medical Center in Cedar City, where doctors used a telephone interpreter service to communicate with the Japanese tourists. Seven were flown to trauma centers in the Salt Lake City area that enlisted volunteer interpreters.

University of Utah Hospital relied on a health care assistant who speaks Japanese, spokesman Chris Nelson said.

Hiroki Hayase, a 20-year-old man from Osaka, was killed in the crash, authorities said. The identities of two others who died — a 38-year-old man and 40-year-old woman, both from Tokyo — have not been released by authorities who are trying to notify relatives in Japan.

The group was on its way to Bryce Canyon National Park when the bus veered off the highway.

Utah troopers said they were working to identify the companies involved in arranging the tour. Troopers also were consulting the Japanese consulate in Denver to notify families of the passengers. A message left with a consulate official wasn't immediately returned late Tuesday.

Nippon Travel Agency in Tokyo told the AP that eight of the passengers were its customers, while two other companies booked the trip for the remaining six passengers.

The bus was provided by Canyon Transportation of Sandy, Utah, company dispatcher Mandy Padilla said. Company officials went to the crash site to conduct their own investigation, she said. It wasn't clear if the driver worked for Nippon, another company or Canyon Transportation. Padilla offered no additional details.

The bus tour started in Las Vegas, made a stop at Utah's Zion National Park and crashed at 6:40 p.m. Monday about 90 miles short of Bryce Canyon, authorities said.

Bryce Canyon is a popular stop for foreigners who account for about half of the 2 million visitors it gets in a year, a spokesman said.

Las Vegas is a busy hub for tourists who set off for western landmarks, including the Grand Canyon, Death Valley and Utah's Monument Valley.

Monday's crash recalled a January 2009 wreck caused by driver distraction that killed six Chinese tourists and the tour driver on U.S. 93 near Hoover Dam. Ten other passengers on the shuttle bus were injured as they were returning to Las Vegas from Arizona's Grand Canyon.

A National Transportation Safety Board report issued in June said that crash might have been prevented if the board's previous recommendations for stability control improvements and lane departure warning system had been adopted by the U.S. Department of Transportation. The NTSB also has called for improved passenger restraints and strengthened windows and roofs on mid-size commercial buses.

NTSB spokesman Nicholas Worrell said the board was looking at Monday's bus crash "in a limited way" because of its similarity to the 2009 crash near Dolan Springs, Ariz. No formal investigation was planned, Worrell said.

The Utah crash happened weeks after a Japanese tourist was killed in Switzerland when the popular Glacier Express train derailed July 23 in the Alps. That crash injured 42 other passengers, most of whom were from Japan.

___

Associated Press writers Jennifer Dobner in Salt Lake City, Ken Ritter in Las Vegas and Ryan Nakashima in Los Angeles contributed to this report.