Bihar state official Abhijit Sinha said another 27 children and the school cook have been hospitalized in Patna, the state capital. Ten of them are in serious condition. The children are age 8 to 11.
They fell ill soon after eating meals in the school on Tuesday in Masrakh, a village 80 kilometers (50 miles) north of Patna. They were rushed to a local hospital and later to the state capital for treatment, Sinha said
The meal was cooked in the school kitchen.
P.K. Sahi, the state education minister, said a preliminary investigation suggests the food had traces of phosphorous, which is used to preserve rice and wheat.
Many state governments in India have launched midday meal programs for poor children. Malnutrition is one of the major health concerns among Indian children.
Bihar state Chief Minister Nitish Kumar ordered an inquiry.
Authorities have suspended a food inspector and registered a case of criminal negligence against the school headmaster.