They were among 12 workers, who were piling sand from the ocean floor in order to build a wharf on the tidal flat off Shipu town of Xiangshan county, said sources with the frontier defense force in the city of Ningbo.

The sand suddenly gave way at around 2:50 p.m. and everyone was washed into the sea, the officials said. Eight people were rescued.

Rescuers are still searching for the four missing, they said.

Heavy rains from typhoon Man-yi and an onrush of tidal water was to blame for the accident.

Man-yi, the fourth strong typhoon of the year, edged off Zhejiang at midday Saturday, but heavy rains and winds sweeping at 60 km per hour continued to batter coastal regions Saturday and Sunday.

Last Tuesday, storms brought by Man-yi sank a Chinese cargo ship carrying 22 crew members about 600 km northwest of Guam. The Chinese Consulate officials said 13 people were rescued, three died and six were still missing.