Nearly 100 students of a Corporation Middle School in Hosur in the district, took ill suddenly post lunch allegedly due to suspected gas leak from a septic tank on the premises, an official said on Friday.

Several of them developed nausea and some vomited in the classrooms but none developed serious symptoms, he claimed.

District Collector V Jaya Chandra Bhanu Reddy, who visited the school and also the hospital where the children were being treated, said the children studying in the Hosur Middle School fainted at around 3.15 pm. They were immediately rushed to Hosur Government Hospital and are being treated.

A total of 67 boys and girls were hospitalised. They would be subjected to tests to ascertain the cause, a senior health official told PTI.

Senior officials from the Pollution Control Board, Hosur Corporation and School Education departments visited the school and held an enquiry.