Police said villagers rushed the students and teachers of Government Junior High School at Kunheda village to the Murad Nagar primary health centre (PHC) after they complained of giddiness and started vomiting. Some of them even fainted.
According to PHC in-charge Vikas Indu Aggarwal conditions of six children were somewhat critical and had been kept under observation.
Ghaziabad District Magistrate Vimal Kumar Sharma said, "I have personally visited the students and teachers admitted to the hospital, and all of them are recovering."
Sample of water from the pump has been sent to laboratory for test. Officials said they were also looking into a rare possibility of underground water being contaminated.
An inquiry has been set up to probe into the matter.
The DM said all sub-divisional magistrates (SDMs) and basic shiksha adhikaris (BSAs) have been directed to check nuts and bolts of all hand pumps installed in government schools in their respective areas and ensure that they are firmly tightened.