SHIJIAZHUANG -- More than 300 school children in northern China were treated for food poisoning late Tuesday night, raising fresh concerns over the sanitary conditions of school canteens.

According to the county government of Zhengding, Hebei province, 74 students who showed the most serious symptoms were hospitalized, but none face life-threatening danger.

The students are from 27 classes at Hongwen primary school, which has 35 classes.

Hospital diagnosis showed that the students were suffering from food poisoning.

Authorities are investigating the causes of the incident.