The students complained of vomiting and nausea after consuming themealat their school at Kandrapara in Dongargarh town, a district administration official said.
When teachers noticed the deteriorating condition of children, they immediately admitted them to Dongargarh government hospital, he said.
After treatment, about 30 of them were discharged while 15 were still under observation, the official said.
"However, the condition of all the children was said to be normal," he said.
Prima facie the children felt uneasy due to food poisoning, the official said.