A passenger bus en route to Vancouver crashed through a guardrail along an icy Oregon highway and plummeted down an embankment, leaving nine passengers dead and more than 20 others injured.

The chartered bus was making its way back from Las Vegas when when at approximately 10:30 a.m. it flew off the ice-covered lanes of Interstate 84 and tumbled 200 feet below, Oregon State Police said.

“It’s a very sad, tragic incident,” Lt. Gregg Hastings told CTV News Channel on Sunday. “Road conditions were described as snow and ice.”

The bus is owned by Coquitlam-based Mi Joo Tour & Travel and had about 40 passengers on board when the accident occurred.

After crashing through the guard rail, the bus slid down the hill and came to rest upright at the bottom of a snowy slope.

More than a dozen rescue workers descended the hill and used ropes to pull passengers from the wreckage in freezing weather.

The bus driver was among the survivors but suffered severe injuries. Police said the driver has not yet spoken to investigators.

The identities of the victims have not been released, but Hasting said it was a “strong possibility” that the bus was carrying Canadian citizens.

The investigation into the crash is expected to take several days, if not weeks.

Hastings said police will be looking into the driver and vehicle to determine the cause of the tragic accident.

St. Anthony Hospital in Pendleton, Ore., located about three hours east of Portland, treated 26 people involved in the crash.

“It’s been a very busy day,” said hospital spokesperson Larry Blanc. He said a number of the crash victims were given CT scans and X-rays.

Officials said five of the patients who suffered severe injuries were later transferred to neighbouring medical facilities. 

I-84 is a major east-west highway through Oregon that follows the Columbia River Gorge.

A woman who answered the phone at a listing for Mi Joo Tour & Travel confirmed to The Associated Press that it owned the bus and said it had been on a tour of the Western U.S.