A suspected food poisoning case on Thursday made over 240 students ill in north China's Inner Mongolia autonomous region, authorities said.

The students at Hui People Middle School in the city of Baotou complained of stomachache and vomiting around 3:30 p.m. after lunch in the school dining hall, said a spokesman with the city government. Some were still receiving treatment at hospital, but were not in any danger.

Around 3,000 students had lunch at the dining hall, and students who got their meals at the No. 3 range became sick afterwards.

Kitchen workers from the No. 3 range are in police custody for investigation.

Located in the city's Donghe district, the school has more than 4,000 junior and senior middle school students, most of whom are ethnic Han.