The accident occurred on the Tongmai suspension bridge on the Sichuan-Tibet highway in Bomi county yesterday, disrupting traffic on the arterial road in the southwestern autonomous region, local officials said.
Two of the missing were local villagers travelling on a truck that fell into the river when a part of the 258 meters long and 31.5 meters high bridge collapsed.
Two hikers, a 24-year-old woman from Jiangsu Province and a 25-year-old man from Anhui Province, were also missing after the collapse, state-run Xinhua news agency reported.
The transport authorities also advised drivers and passengers to be alert as natural disasters are frequent on the Sichuan-Tibet road in the rainy season, the report said.