PENDLETON, Ore. (AP) -- A federal agency said Monday it is sending investigators to Eastern Oregon to look into a deadly crash in which a tour bus returning to British Columbia from a trip to Las Vegas spun out of control on an icy interstate, slammed through a guardrail and plummeted 100 feet down an embankment, killing nine people and sending at least 30 others to hospitals.
The Sunday morning crash occurred near a spot on Interstate 84 called Deadman Pass because of the hazards on that stretch of road, a steep seven-mile descent out of the Blue Mountains. That section of highway has "some of the most changeable and severe weather conditions in the Northwest," according to an advisory published by state transportation officials.
Some of the passengers were exchange students from South Korea. Others were from Canada and from Washington state, hospital officials said.
One survivor, 25-year-old Yoo Byung Woo, told The Oregonian that he and other passengers thought the bus driver wasn't driving as slowly as he should have been for the conditions.
"I felt like he was going too fast," Yoo said. "I worried about the bus."
Yoo said it was snowing and foggy as the bus traveled west. One of the riders, who was frightened, asked if they could take another route, Yoo told the newspaper. Some passengers were dozing when the driver slammed on the brakes.
Rocks smashed through windows after the bus crashed through a guardrail and rolled down a slope, Yoo said.
The NTSB said the 1998-model bus rolled at least once.
A hospital official said it appeared 46 people were aboard the bus, and the 37 survivors were sent to hospitals.
Fourteen of those aboard were at St. Anthony Hospital in Pendleton Monday morning, one in serious condition, said spokesman Larry Blanc. Seven were discharged Sunday.
Blanc said 16 people were sent to other hospitals in the region, including the Oregon Health & Science University hospital in Portland.
Umatilla County Emergency Manager Jack Remillard said the bus was owned by Mi Joo Tour & Travel in Vancouver, B.C. A bus safety website run by the U.S. Department of Transportation said Mi Joo has six buses, none of which have been involved in any accidents in at least the past two years.
The bus driver was among the survivors but had not yet spoken to police because of the severity of the injuries he suffered.
Another passenger, who declined to give his name, told The Associated Press he was asleep when the bus went out of control.
"Suddenly people were screaming and the bus (went) down the hill," said the 22-year-old passenger. "I woke up. I feel I'm dying. I grab the seat. Finally the bus stopped."
The man, who lives in Seoul, said he's been studying English at a Vancouver university since November. He and five friends joined a nine-day bus tour of the western United States that included stops in Seattle, Portland, San Francisco and Las Vegas. All of his friends survived.
More than a dozen rescue workers descended the hill and used ropes to help retrieve people from the wreckage in freezing weather.
The NTSB said two investigators were expected to arrive at the crash site Monday. It said they will be looking into why the bus left the road, the condition of the road at the time, the condition of the guardrail, and operations of the company that owns the bus.
A spokesman for the agency, Peter Knudson, said seatbelts aren't required on such buses. "We have been concerned about this for some time," Knudson said.
The local Red Cross shelter has been offering food, clothing and hotel arrangements for survivors as they are released from the hospital. Relatives of bus passengers also have gone to the shelter, seeking information about their loved ones.
Jake Contor, a Pendleton resident who speaks Korean and helped translate for the Red Cross, said he's spoken with several crash survivors.
"The stories have been fairly consistent: braking, swerving, sliding on the ice, hitting the guard rail then sliding down the embankment," Contor said.
Contor said the victims told him that the bus left Boise Sunday morning and was supposed to arrive in Vancouver that night. The survivors who spoke to Contor were seated at the back of the bus and said it appeared that the front and center of the coach sustained the most damage.
County Commissioner Dennis Doherty said his heart goes out to the families.
"The anguish people must be feeling," he said. "Just imagine how you'd feel if you were in Korea and you got a call, there was this huge accident."
I-84 is a major east-west highway through Oregon that follows the Columbia River Gorge.