A sand barge struck a bridge over the Xi River between Heshan and the town of Jiujiang in Guangdong yesterday morning, bringing down a section of the structure at least 200 metres long.
Most of the vessel was submerged under the collapsed sections of the Jiujiang Bridge, forcing its stern out of the water.
'There were 10 crew members on the boat,' Nanhai district propaganda office spokesman Mai Shaoqiang said.
'Two had a few scrapes while the rest were fine.'
Mr Mai said the 1,590-tonne barge, carrying about 2,000 tonnes of sand, had illegally steamed into the main channel and struck a bridge support at about 5am.
Local media reported at least six vehicles had plunged into the river.
The Yangcheng Evening News said two road workers on the bridge when it was hit were missing, but Mr Mai said that had not been confirmed. 'We are using sonar to search for people and the vehicles that might be missing in the accident,' he said. 'We also sent divers down, but nothing has been found so far.'