LANZHOU - Thirty-four pupils were hospitalized over suspected food poisoning in Northwest China's Gansu province, a teacher and doctor confirmed on Tuesday.

The students, from Duanjiatan Primary School in Lanzhou, capital of Gansu, were sent to the Gansu Provincial People's Hospital after they fell ill and vomited during class on Monday afternoon, a teacher with the school said.

Thirty of them were discharged from hospital and returned home late Monday night. The remaining four, who had serious symptoms of sickness, were still being treated in hospital. Doctor Lei Xiaoyan said they probably suffered food poisoning.

The teacher said all of them had their lunch on Monday in a small restaurant near the school. Local authorities are investigating the incident.