Officials in eastern India say at least 22 children have died after eating a free lunch cooked in the school's kitchen.
Bihar state authorities say at least 27 other students were hospitalized after eating a meal that included rice and lentils Tuesday at a primary school in Masrakh, about 90 kilometers north of Patna, the state capital. Several of the children, who were between the ages of four and 12, remain in serious condition.
"The doctors have said that two children are still critical and the rest are out of danger. They are saying that some poisonous substance was mixed in the meal which has led to the incident. It is very sad that so many children died in the incident."
Angry demonstrators staged a protest following the children's deaths.
An education minister says a preliminary investigation indicates the food contained traces of an organophosphate used as an insecticide. The cook who prepared the meals, and also fell ill, says she noticed something strange in the cooking oil that was used.
"When I saw the oil it looked like it had a layer at the bottom of the jar. I thought that this is locally made oil as often there is an accumulation of residual waste at the bottom when the oil is domestically prepared. Generally we get just about enough oil to prepare one meal, as there is no space for storage."
The state government says it is investigating the incident.
Many state governments have launched midday meal programs for millions of poor children. Malnutrition is a major health issue for Indian children.
UNICEF says one in every three malnourished children in the world lives in India. The United Nations says malnutrition is more common in India than in sub-Saharan Africa.
Malnutrition in early childhood has serious, long-term consequences because it impedes motor, sensory, cognitive, social and emotional development.