When the tour bus carrying Janice Wong's family and dozens of other tourists stopped rolling along a mountain highway in British Columbia, the 19-year-old found herself in a writhing heap of people catapulted from the vehicle.

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American citizens Janice Wong and father James Wong, from Los Angeles shop for new clothes at a Target store in Kelowna, B.C. on Friday after their tour bus crashed on the Coquihalla Highway south of Merritt, B.C., on Thursday. (Tamsyn Bergmann/Canadian Press)

The scene was so bloody and dusty she couldn't tell who was who. She screamed out for her parents.

"I couldn't see — I was panicking at the same time," Wong said in an interview.

"I was like, 'I don't know what the hell just happened. Where's my parents? Holy crap. Are they dead?' It was just blood everywhere."

Wong and her parents, American citizens from Los Angeles who were in B.C. for a holiday, were among 56 people on a tour bus that was returning to the Vancouver area from a trip to the Rocky Mountains.

Coquihalla Super Vacation tour bus crash - Aug. 28, 2014

All 56 people on the bus were injured. By Friday, seven people were listed in critical condition and six others were in serious condition. (CBC)

The bus crashed Thursday afternoon about 30 kilometres south of Merritt, B.C., about a three-hour drive from Vancouver.

Everyone on the bus was injured, and 55 of them were treated in various hospitals throughout the region. By Friday, seven people were listed in critical condition and six others were in serious condition, while 19 had been discharged.

Wong and her father were treated for minor injuries at the hospital closest to the accident in Merritt, but her 56-year-old mother was airlifted to Kelowna where she underwent surgery. Wong said her mother remained in the intensive-care unit.

"It's a miracle I'm perfectly fine. A little too lucky. Just a little too lucky," Wong, who just visited her mother in the Kelowna hospital, said as tears welled in her eyes.

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A patient is brought in from the accident scene via air ambulance. (CBC)

Wong's father remembers tumbling in the bus and then bleeding, but said he knew how to handle the terrifying scenario because he fought as a soldier for the U.S. in the Vietnam War.

"The scratches are OK," said James Wong, 68, who was wearing someone else's glasses and clothing still spattered with blood.

"But life is life. When (something) comes, it comes. We can't expect anything. That's the way I look at it."

Speed, road conditions ruled out as causes

The RCMP had to pinpoint the cause of the crash. Investigators said Friday that video footage from a dashboard camera allowed them to rule out speed or road conditions.

"It's more an issue that the driver drove into the centre median and then veered too hard trying to get onto the road," said Sgt. Brian Nightingale.

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American citizens Janice Wong and father James Wong, from Los Angeles suffered non life-threatening injuries, while their mother/wife remains in Kelowna General Hospital ICU. (Tamsyn Bergmann/Canadian Press)

"We're doing mechanical (inspections) today on the bus, so that will rule out any kind of mechanical factors, like steering and braking and that kind of stuff."

The RCMP said in a news release that several children were on the bus, but none suffered serious injuries.

The release said passengers on the bus were from Canada, the United States and China, but they did not have a detailed breakdown of the passengers' nationalities.

The passengers were on a tour organized by Super Vacation, a company based in Richmond, B.C., which describes itself as the largest Chinese tour operator in North America.

Company spokesman L. Lau said the bus left Golden, B.C., on Thursday morning and was en route to Vancouver. The crash scene is more than five hours southwest of Golden.

Lau said many of the passengers are from mainland China, Hong Kong and Taiwan, though he said some are from B.C. and elsewhere in Canada. He said the company had been in touch with some of the passengers and was figuring out ways to provide assistance.

"We have been planning for everything right now," said Lau, who declined to give his full name. "Of course, some of the patients we can't see."

Tourists, children injured in B.C. tour bus crash3:42

Some passengers continued to Vancouver

On Friday, some of the passengers continued by bus to Vancouver, he said.

Lau said the bus was operated by Western Bus Lines, which he said is a "major local bus company with 35 years of experience." Someone who answered the telephone at the Western Bus Lines office in Kelowna said the company had no comment and then hung up.

"We are waiting for the police report," Lau said.

Abraham Lin, director of consular services for the Taipei Economic and Cultural Office in Vancouver, said his office had confirmed two of the patients are Taiwanese nationals, a 20-year-old man and a 21-year-old woman.

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A Commercial Vehicle Safety and Enforcement officer walks past the crashed tour bus during an investigation at a towing company lot in Kelowna on Friday. (Darryl Dyck/Canadian Press)

"They are just studying for the summer and they joined the bus tour for the Rocky Mountains," Lin said.

Lin said his office had been in touch with one of the Taiwanese passengers and had contacted the other's parents in Taiwan.

The Chinese consulate in Vancouver said it had confirmed some of the passengers are from China, but he said officials were still working to confirm precise numbers.

A spokeswoman for the U.S. consulate in Vancouver said the consulate had contacted the Royal Inland Hospital in Kamloops and was told there were no American citizens at the facility. American officials hadn't yet been able to reach other hospitals.

Photos from the scene on Thursday showed the white bus upright, with visible damage to its side and the Western Bus Lines logo mostly scraped off. Passengers and emergency workers could be seen standing alongside the bus, with debris strewn about the road.