Police in Oregon say it could be more than a month until investigators know what caused a bus driven by a 54-year-old Vancouver man to plummet down a steep embankment, killing nine people and injuring dozens of others, including several B.C. residents.

The B.C.-bound bus flipped over a guardrail and plummeted more than 60 metres, west of an area called Deadman Pass. Earlier reports suggested it was more than 30 metres, but police now say it was at least a 60 metre plunge.

The area is well known locally for its hazards, including slick conditions like snow and black ice and poor visibility.

Forty-eight people, including the driver, were aboard the bus, said Oregon State Police Lt. Gregg Hastings during a Monday news conference. Initial reports said the number of passengers was between 40 and 49. The passengers were between 7 and 74 years old.

Thirty-nine people were treated at local hospitals. At least one is in serious condition, and ten have been released.

Lt. Hastings said although the highway was icy and snowy, the weather wasn't immediately being blamed for the crash, but police are still investigating all possibilities, including weather, speed, vehicle condition and the bus company's safety record.

The driver of the bus owned by Mi Joo Tour & Travel in Vancouver survived the crash but was so severely injured that he couldn't give any information about it, said police. The driver was the only one on board wearing a seatbelt, said Lt. Hastings, adding passenger seatbelts are not required on these types of buses.

It is unclear how long the driver was operating the vehicle before the accident, said Lt. Hastings, but it appears the bus travelled from Las Vegas to Boise before continuing towards Vancouver.

Questions about speed

It is also unclear how fast the bus was travelling, he said.

The Oregonian newspaper quoted one survivor, Yoo Byung Woo, 25, as saying he and other passengers thought the bus driver was "going too fast."

The lieutenant said speed would be part of the investigation.

Once emergency officials have moved the bus from the bottom of the embankment to a secondary location, it will be subject to:

• A mechanical inspection.
• Photographs.
• Personal property gathering to return to victims and next of kin.

After the investigation is completed, police will consult the district attorney's office and decide whether to press charges against the driver.

Mi Joo Tour & Travel has a satisfactory safety rating, according to U.S. Department of Transportation safety records, and has not recorded any accidents over the past two years.

2nd crash on same highway that day

Tim Trainor, an East Oregonian photographer and assistant city editor who arrived onsite about one hour after the accident, told CBC News that Sunday was a clear day, with some fog in the morning, but the temperature — around the freezing mark — gave him reason to believe there was ice, slush and snow on the road.

"[It was] right on that freezing level where it was half rain half snow," he said. "It definitely made for treacherous driving.”

The National Transportation Safety Board is sending investigators to the site, according to a press release. The investigation will look at "why the motorcoach left the roadway, the condition of the roadway, the highway barrier and the operations of the motor carrier."

The NTSB is an independent agency responsible for investigating significant transportation-related accidents, according to its website. It identifies probable cause and "issues safety recommendations aimed at preventing future accidents."

It was the second fatal accident on the highway on Sunday. A 69-year-old a man died in a rollover accident about 50 kilometres west of the bus crash.

Authorities have determined icy road conditions caused the rollover accident, Gaviola reported.

Survivors feared for their lives

Berlyn Sanderson, 22, of Surrey, said she and several other passengers were ejected from the vehicle.

"It's kind of like one of those dreams you have of the world ending," she told The Associated Press.

"When I opened my eyes ... I thought all of the people on the bus were dead because the bus was totally broken down," said Jaemin Seo, a 23-year-old exchange student from Suwon, South Korea, studying in Vancouver. He was also ejected from the bus and suffered a broken ankle and a gash in his arm that required stitches.

Two teens, 16 and 17, spoke through a translator to recount their experience to the Oregonian and the East Oregonian. They have been living with host families in Vancouver since moving from South Korea two years ago, said Trainor. Police have not yet identified the teens as B.C. residents.

The boys were seated near the back of the bus when it swerved a few times, hit a highway guardrail and flipped, plummeting down an embankment.

"I thought I was going to die," the 17-year-old is quoted as saying. Both teens declined to give their names.

The bus landed at the bottom of a snowy slope, beaten and battered but upright with little or no debris visible around the crash site.

The Oregonian says the 17-year-old had a broken collarbone and had his arm in a sling, and the 16-year-old was not injured. Both were released Sunday night to a makeshift shelter.

Language barrier causing difficulties

Police are having a hard time identifying the victims and their families, said Trainor.

A Las Vegas to Vancouver bus hit a highway guardrail, flipped and plummeted more than 30 metres down an embankment Sunday in Oregon, killing at least nine people and injuring dozens. ((Tim Trainor/East Oregonian))

"Most of the people are from Korea, Taiwan and Japan," he said via phone from Pendleton. “A lot of them don’t speak any English.”

Some passengers only had Korean passports on them, said police.

Officials from the South Korean consulate from Seattle have been helping as translators, said Lt. Hastings, and working with police to help identify victims.

Oregon police have asked the Mounties to help notify relatives of the crash victims in the Vancouver area, said RCMP Sgt. Peter Thiessen, adding that some family members could live outside the Lower Mainland area.

Thiessen did not specify the number or nationality of victims. The names of the deceased have not yet been released.

With files from The Associated Press and The Canadian Press