CHONGQING - More than 90 pupils at a primary school in Southwest China's Chongqing municipality have developed symptoms of diarrhea and felt unwell since Friday afternoon, local authorities said on Saturday.

Ninety-one students of the Central Primary School of Nanping Township, Nanchuan District were sent to hospital for treatment after they have developed the symptoms.

As of Saturday afternoon, two students have been diagnosed with bacillary dysentery, and the 89 others are suffering from similar symptoms to bacillary dysentery.

A local hospital said that no student was in critical condition.

The cause of the incident is under investigation.