A case of attempt to murder was registered against unknown persons in this regard, they said.
The incident occurred in Barengedgi village of Birkur mandal this noon when the school children and teachers drank water stored in the tank, a police officer said.
As they complained of stomach ache, they were rushed to a hospital and were kept under observation before given discharge.
Birkur Mandal Tahasildar Anjaiah lodged a complaint with police in this regard stating that an unknown offender mixed some poisonous substance in the water and sought for necessary action in this regard, the officer said.
Following a complaint, the Birkur police registered a case of attempt to murder under section 307 of IPC and efforts are underway to nab the culprits.
