Earlier this week, tragedy struck the state of Bihar in northern India. Over 23 students died from food poisoning after a mid-day school lunch service. The Bihar students, aged between 5-12 years reacted immediately after food ingestion. Officials believe the poison was an organophosphorus compound, a type of chemical that the U.S. Centers for Disease Control and Prevention says is commonly used in agriculture. It's a nerve agent related to sarin gas, which is used in chemical warfare, the U.S. Health Department says. Exposure to a high dose can cause an irregular heartbeat, difficulty breathing, paralysis and seizures. Bihar state Education Minister P.K. Shahi said he heard reports that the cook had questioned the quality of the oil she was supposed to use, but was overruled by the school's headmistress."The information which has come to me indeed suggests that the headmistress was told by the cook that medium of cooking was not proper, and she suspected the quality of the oil," Shahi said. "But the headmistress rebuked her, and chastised the children, and forced them to continue the meal." Investigations have been under way but it is still unclear whether the incident was accidental or intentional.