Parents in the Indian state of Bihar are demanding answers after 23 children died on Tuesday and Wednesday after eating a tainted meal at a school in the village of Dharmasati Gandaman.  

Over 47 primary school-aged children became ill on Tuesday after eating a free school meal of rice, lentils, and vegetables as part of India's Mid-Day Meal program, which is designed to tackle hunger amongst school children and increase attendance in schools. 

The children, aged four to 12, became ill very quickly and died after vomiting and convulsing from "agonizing stomach cramps," according to Reuters. Some children were affected so quickly that they died in their parent's arms while being taken to the local hospital.

Police are searching for the headmistress of the school after she vanished on Tuesday.  Villagers said that her school purchased the ingredients for lunch at the headmaster's husband's grocery store.

Nineteen of the 23 deceased children were buried on Thursday and 25 children remain in the hospital and are likely to recover.

According to the BBC, a doctor at a local hospital in the village said a chemical found in pesticides was "the likely cause of contamination." Medical examiners said that the organophosphate, used as an insecticide on rice and wheat crops, was either in the food or cooking oil. Officials are still waiting for lab results for more details about the chemicals.

Angry parents said they want the graves to be a symbol of "government negligence" and some joined protests against the deaths.  Four police vehicles were set on fire on Wednesday in the protests.

Children throughout Bihar were refusing their free midday meals on Thursday and local officials have ordered headmasters to taste food and check food safety to dispel any fears that the lunches are unsafe.

Critics have said that this response by the state solves little, as schools were required before the incident to follow food safety procedures. These rules, they say, are rarely followed or enforced.

The Mid-Day Meal program in India reaches 120 million children in 1.2 million schools across India, according to the Indian government. The school in Dharmasati Gandaman was formed in 2010 and taught 125 children.

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