CHENGDU -- One hundred and forty-three students have fallen ill with diarrhea after eating lunch at a school in southwest China's Sichuan Province, local health authorities said Thursday.

The patients, all students of the Yuquan School in Yuquan Township, Mianzhu City, suffered diarrhea, nausea, vomiting, bellyache and low fever after eating lunch and went to local hospitals on Tuesday, a spokesman with the Mianzhu health bureau said.

Seventy-three students have been hospitalized and 70 others are staying at school for observation, the spokesman said.

They are all in stable condition, he said.

Initial investigation shows that most of the sick students ate lunch at the school dining hall and a few had meals at food booths nearby the school.

Local health authorities have obtained food samples from the school dining hall and the food booths, the spokesman said.

The results will come out in a few days, he said.

The Yuquan School has about 1,300 students, including 200 children of the kindergarten. The rest are primary and junior high school students.

The kindergarten children were not involved in the incident, the spokesman said.

Local health authorities has ordered an overhaul of the food safety in all schools of the city, he said.