By JONATHAN J. COOPER

Associated Press

PENDLETON, Ore.

--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 200 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.

The bus driver was among the survivors but had not yet spoken to police because of the severity of the injuries he suffered.

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.