(CNN) -- At least 253 students are undergoing treatment following suspected food poisoning this week in northern China, state media reported.
In addition to students, two teachers were also hospitalized, Xinhua news agency reported.
The incident occurred Thursday at a middle school in Baotou, which is in China's inner Mongolia autonomous region.
Victims suffered various symptoms, including stomach ache and vomiting after eating at the same counter in the school dining hall, the news agency said Friday.
Employees who work at that counter are in police custody undergoing questioning, according to Xinhua.