The death toll from a bus accident in the Xinjiang Uygur autonomous region rose to 15 on Wednesday.

Twenty passengers in the bus suffered injuries and are still being treated. Four are in critical but stable condition.

The male bus driver survived the crash and is being treated at a local hospital.

The tour bus carrying 35 female passengers plunged into a valley on Tuesday, falling more than 40 meters.

The accident occurred around 5:10 pm when the bus was returning from a tourist spot near the Changji in the Changji Hui autonomous prefecture. The bus fell into a valley near Miaoergou township, Rehmanjon Dawut, deputy governor of the prefecture, said during a news conference on Wednesday.

The 15 people killed in the accident ranged in age from 18 to 49.

The bus was one of 10 rented by a local shopping mall to take more than 360 of its employees on a tour.

"I've been at the bedside of my wife and talked about our happy times during the past to help her recover," said Jiang Zhibo, whose wife Xiao Yonghong was injured in the accident.

Qing Hong, who was injured in the accident, recalled the moments leading up to the wreck. "I was sitting in the last row when the left side of the bus began to fall after it made a turn on the mountain road. Then it suddenly began to tumble and I just held tight to the seat. When the bus rolled over for the second time, I was thrown out of the bus and held onto a big rock," said Qing, a sales assistant.

Qing fainted and woke up in the hospital.

With the help of more than 30 local herdsmen, rescue workers lifted all of the passengers from the valley within 45 minutes after arriving at the scene, Rehmanjon said.

"The investigation showed that the bus wasn't overloaded, and heavy fog that reduced visibility was to blame for the accident," said Xie Bin, political commissar of Changji public security bureau. Also, the mountain road with sharp curves had become slippery because of rain during the day on Tuesday and the driver might have not reacted properly to the conditions, he added.

Four people died at the scene, while 11 others died at a hospital. The identity of one of the dead remains unclear due to severity of the person's injuries. One of the victims is a Muslim from the Hui ethnic group and will be buried according to tradition, Rehmanjon said.

Relatives of some of the victims have already begun to conduct mourning services at one of the funeral homes in Changji city.

The shopping mall was open as usual on Wednesday. The company has allocated 20 million yuan ($3.3 million) to help the victims' families. Those responsible for the accident will be dealt with according to law, the local government said.

Contact the writers at maoweihua@chinadaily.com.cn and cuijia@chinadaily.com.cn