Seven sanitation workers died during an attempt to dredge a cesspool in Huaibei City, in east China's Anhui Province, on Sunday afternoon.

The seven had been assigned to dredge the cesspool at a company on Nanli Road, Huaibei.

One worker went down the inspection shaft but failed to emerge for some time. The other six followed in an attempt to rescue the first but without taking protective measures, according to the Huaibei city government.

Local police were notified at 2:48 p.m. Police, first-aid workers and fire control officers rushed to the site but found all seven workers had suffocated to death.

A preliminary investigation indicated that toxic gas might have caused their deaths. A further investigation is under way.

(Xinhua News Agency June 30, 2008)