TAIYUAN -?At least 152 people were trapped after a coal mine being built in north China's Shanxi Province was flooded Sunday, local authorities said.

A total of 261 workers were in the pit of Wangjialing Coal Mine when underground water gushed in at about 2:30 pm, the provincial work safety supervision administration said.

About 109 workers have escaped unharmed while 152 others remained trapped in the shaft, according to the provincial emergency response office.

The mine, sitting astride Xiangning County of Linfen City and Hejin City of Yuncheng City, covers about 180 square kilometers.

The mining zone boasts more than 2.3 billion tonnes of coal reserves, including nearly 1.04 billion tonnes of proved reserves, according to the company's official website.

It is undergoing infrastructural construction and is expected to produce 6 million tonnes of coal annually once put into operation.

The mine, affiliated to the state-owned Huajin Coking Coal Co Ltd, is a key project approved by the provincial government.