The incident was reported from primary school in Rohini sector 21, where the four tasted the midday meal comprising halwa-chana before serving it to the children.
The food, prepared by Maitri Research and Development Foundation, was first tasted by the school principal, teacher in-charge of midday meal and two members of the NGO.
The food tasting was done half-an-hour before serving the meal to children to ensure that the quality of food is good.
The three were taken to a hospital for check-up and did not require any further treatment.
The corporation clarified that the same NGO supplies midday meal to 56 other schools in Rohini and Sadar Paharganj but no such complaint was received from any other place.