Rescuers work at the accident site after a bus overturned and plunged into a deep valley along the highway connecting Dali City and Baoshan City, in Laoying Township of Baoshan City, southwest China's Yunnan Province, March 18, 2013. At least 13 passengers were killed and 15 injured in the accident that occured at 4:25 p.m. (0825 GMT) on Monday. (Xinhua/Zhang Xulong)

Rescuers transfer an injured passenger at the accident site after a bus overturned and plunged into a deep valley along the highway connecting Dali City and Baoshan City, in Laoying Township of Baoshan City, southwest China's Yunnan Province, March 18, 2013. At least 13 passengers were killed and 15 injured in the accident that occured at 4:25 p.m. (0825 GMT) on Monday. (Xinhua/Zhang Xulong)

Rescuers work at the accident site after a bus overturned and plunged into a deep valley along the highway connecting Dali City and Baoshan City, in Laoying Township of Baoshan City, southwest China's Yunnan Province, March 18, 2013. At least 13 passengers were killed and 15 injured in the accident that occured at 4:25 p.m. (0825 GMT) on Monday. (Xinhua/Zhang Xulong)

Rescuers work at the accident site after a bus overturned and plunged into a deep valley along the highway connecting Dali City and Baoshan City, in Laoying Township of Baoshan City, southwest China's Yunnan Province, March 18, 2013. At least 13 passengers were killed and 15 injured in the accident that occured at 4:25 p.m. (0825 GMT) on Monday. (Xinhua/Zhang Xulong)