More than 150 students in Lianyuan, Hunan province, were sent to a hospital complaining of diarrhea and nausea on Tuesday night after dining at school, Xinhua News Agency reported on Wednesday.

Twenty-seven of the students remain hospitalized. It is suspected that the milk the school offered may have caused the food poisoning.

On May 6, three students at another school in the city complained of nausea, and local authorities believe the reason was that the school’s canteen used rice flour that had gone bad to prepare breakfast.