A senior work safety official's grin at the site of a deadly traffic accident in Shaanxi province has become a nightmare haunting him.

Yang Dacai, 55, head of the Shaanxi Provincial Bureau of Work Safety, was seen to be grinning in a photo taken after he arrived at the scene of a deadly traffic accident on Sunday in Yan'an, Shaanxi. Thirty-six people were killed when a sleeper bus rammed into a truck carrying a tank of methanol and caught fire.

The photo triggered an online wave of criticism among netizens.