SHANGHAI, Aug. 14 -- AT least 22 people were killed after an under construction bridge collapsed in central China's Hunan Province yesterday afternoon, Xinhua news agency reported.

Rescuers are searching for 46 missing people, Xinhua said. It said 123 people were working at the site in Fenghuang County when the 328-meter bridge collapsed about 4:40pm yesterday. Fifty-seven people survived the accident with 22 of those injured.

Police detained project manager Xia Youjia and the site's inspector Jiang Ping last night.

Xia is a vice manager with a branch company of Hunan's Road & Bridge Group and Jiang is an employee of an inspection company attached to the province's Communications Planning, Survey and Design Institute.

Police also sealed documents and materials about the project for further investigation.

A tourist from Wuhan City of Hubei Province told the local-based Changjiang Times that no reinforcing steel bars could be seen inside the broken piers.

"It's so strange and so regretful," the witness surnamed Wang said. "A bridge that looked so great in the morning is now gone."

Several woman tourists cried at the scene.

The bridge over the Jiantuo River was to open at the end of this month and workers started removing scaffolding on July 15, the report said.

A local company invested 12 million yuan (US$1.59 million) to build it.

Hunan governor Zhou Qiang has reached the scene and the cause of the accident is under investigation, Xinhua said.

Fenghuang is a well-known tourist destination.