Some 20 pupils of Sekolah Kebangsaan Tanjung Bungah here were rushed to a nearby clinic after eating tomato rice in their school canteen.
The standard four, five and six pupils began vomitting and complained of stomach ache upon returning to their classes after recess.
They were rushed to the clinic about 11am when their condition worsened.

A medical assistant at the clinic, who declined to be named, confirmed the students suffered from food poisoning and said they were allowed to return home after checks.
He said the pupils were given medication and their condition improved soon after.
A standard four pupil, Nursyamira Sazleen Salim Shah, said she and eight other classmates started throwing up and experienced stomach ache upon returning from the school canteen.
“I knew something was wrong when I ate the rice and it tasted funny.
“We all started vomitting after eating the rice. Some of my friends started crying and I was concerned over a friend who was suffering from asthma,” she said.
Nursyamira said the situation became chaotic when more pupils started showing symptoms of food poisoning.
Another pupil, Amir Fakry Zulkhibri said he felt better after taking some medication.
“I started feeling giddy after eating the tomato rice and some fried chicken. A teacher later asked us all to gather at the guard post before sending us to the clinic,” he added.