Outraged residents took to the streets in India’s Bihar state as more children succumbed to a lethal poison unintentionally served to them by their school for lunch.

By late Wednesday, the death toll had climbed to 22 and dozens more were critically ill after consuming a free meal provided by their school in Saran district.

Most of the victims were under the age of 12, triggering an outpouring public outcry and grief.

Hundreds of people, armed with poles and sticks, blocked streets and railway gates as more details surrounding the school poisoning emerged.

Initial investigations suggest that organophosphorus, commonly used in farm pesticides, may have been mixed into the rice, beans and potato curry served Tuesday at the state-run elementary school in an impoverished village in Bihar, the Wall Street Journal reports.

P.K. Shahi, the state’s education minister, said the school’s cook noticed a strange color and foul smell from the cooking oil when preparing lunch.

The cook was taken ill after tasting the food and later died.

Although it remains unclear how and where the chemical got into the food.

Police were looking for the school’s headmistress who reportedly bought provisions for school meals at her husband’s grocery store.

But attempts to reach the headmistress and her husband were unsuccessful. Police said she may have fled after the deaths for fear of the parents’ reaction.

The victims were rushed to hospitals after suffering from vomiting, fainting and foaming at the mouth.

“Looking at the critical condition in which they were brought to the hospital, it seems like there were large quantities of poison in the food they consumed,” said K.M. Dubey, a doctor at the hospital where some of the children were taken.