Ten workers went missing after they fell off a broken platform in a coal mine in Gansu province on Thursday evening, local authorities said. The accident happened in the Huacaotan Coal Mine in Shandan county, Zhangye city, according to local authorities. The workers fell off the platform after it overturned more than 200 meters above the bottom of the shaft, authorities said, adding that the mine was under construction when the accident happened, Xinhua news agency has reported.