Officials in eastern India say at least 20 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. Ten of those children are in critical condition.
Angry demonstrators staged a protest following the children's deaths.
An education minister says a preliminary investigation indicates the food contained traces of phosphorous. Few other details were immediately released.
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 U.N. 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.