The crash took place on Interstate 84 east of Pendleton, Oregon State Police said. Emergency responders, including people trained for rope rescues, were on the scene to help move victims back to the highway.
The injured, including the bus driver, were transported to area hospitals with a range of injuries. The cause of the crash is under investigation. The driver suffered severe injuries and has not yet spoken to authorities, police said.
About 40 people are thought to have been aboard the charter bus, which was returning to Vancouver, British Columbia, from Las Vegas, police said. The bus was operated by Mi Joo Tour & Travel out of Vancouver.
Westbound lanes of I-84 were closed near the crash site.
CNN's Lateef Mungin contributed to this story.
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