HOHHOT, Oct.1 -- A total of 217 students from a middle school in north China's Inner Mongolia Autonomous Region have been struck with food poisoning after eating at their school, local police said Sunday.

The public security bureau of Fengzhen City said students at the Experimental Middle School of Fengzhen City developed symptoms such as dizziness, headaches, fever, vomiting and diarrhea Friday morning. By early evening 82 students had been admitted to hospital.

The city's Party and government authorities put into effect public health emergency response measures and sent all 217 students with food poisoning symptoms to hospital for observation.

By Sunday morning, 107 students has been discharged from hospital. All the students who remain in hospital are in stable conditions.

An investigation shows that food prepared for the students at their school on Thursday was mixed with days-old food which health workers says had already turned bad.

Local police have detained seven administrative workers at the canteen on Saturday night. The city government has suspended school principal, Suo Jianmin, who may face further disciplinary action.

Fengzhen, is more than a three-hour bus ride from Hohhot, the regional capital.