SHANGHAI: Some family members of the Chinese tourists who were killed or injured in a bus accident in Arizona on Friday will leave for the United States this afternoon, an official said here Monday.

Wu Shougui (left), Bao Ruihua and their 8-year-old son Wu Shuang leave the University Medical Center in Las Vegas on Sunday afternoon. The family suffered the lightest injuries among the passengers involved in Friday's deadly bus accident. [China Daily]

Yang Jing from the Shanghai municipal tourism administration, told China Daily the families will leave in two groups.

"The first 15 handed in their visa applications this morning and those that have been approved will leave tomorrow afternoon," she said.

A statement published on the administration's website said an airline, the name of which was not mentioned, has reserved seats for the families.

Yang refused to give any details of the flight.

"We could encounter legal issues when dealing the issues, and there may be differences between Chinese and American law. A lawyer will be responsible for communicating with both sides," Yang said.

"The lawyer will also be responsible for conveying the family members' requests to the proper parties.

"The doctor will be on hand in case anyone becomes sick. Some of the people traveling are very old," she said.

On Friday, a bus with 15 Chinese tourists, a driver and a tour guide overturned on a highway just south of the Hoover Dam, following a visit to the Grand Canyon. Six people died at the scene and the a seventh died at the University Medical Center.

As of Sunday, most of the 10 people injured were still in hospital.

The condition of the 48-year-old driver has been upgraded from serious to fair.

A six-member investigative team is hoping to talk to him and the passengers as soon as they recover sufficiently.

The investigation will take 12 to 18 months to complete, US National Transportation Safety Board spokesman Peter Knudson was quoted as saying by the Associated Press.

The University Medical Center in Las Vegas said some local Chinese communities have been offering the victims places to stay, and providing interpretation services.

Shanghai's Vice-Mayor Zhao Wen said Monday that tourism firms must pay more attention to safety.

"A lesson must be drawn from the accident," she said.

China Pacific Life Insurance has already paid out 1.85 million yuan ($270,000) to families of those killed in the accident.