Another mass food poisoning case has been reported in India. At least 23 students in the southwestern coastal state of Goa were treated at a hospital after they were sickened during lunch, police said.

Earlier this week, 23 students died and 25 people were hospitalized from food poisoning during a school lunch in northern India’s Bihar state.

Two children of the chef at the school were among those who died, CNN’s sister network CNN-IBN has reported.

Earlier this week…

At least 22 children have died and dozens more have fallen sick after eating a tainted school meal in India’s eastern state of Bihar. The poisoning occurred at a government school in the village of Masrakh in Saran district.

India’s Mid-Day Meal Scheme provides free food to try to boost attendance, but often suffers from poor hygiene. The Mid-Day Meal was first introduced for poor and disadvantaged children in the southern city of Chennai in 1925.

The Mid-Day Meal is the world’s largest school feeding programme, reaching 120 million children in 1.2 million schools across the country, according to the government.

Twenty eight sick children were taken to hospitals in the nearby town of Chhapra and the state capital, Patna, after the incident. A total of 47 students of a primary school in Dharma sati Gandaman village fell sick on Tuesday after eating the free lunch.

The state education minister, PK Shahi, told the BBC a preliminary investigation indicated that the food was contaminated with traces of phosphorous.

“The doctors who have attended are of the tentative opinion that the smell coming out of the corpses suggests that the food contained organo-phosphorous, which is a poisonous substance,” he said.

“Now the investigators have to find out whether organo-phosphorous was accidental or there was some deliberate mischief.”

Earlier, doctors treating the patients had said “food poisoning” was the cause of the deaths.

“We suspect it to be poisoning caused by insecticides in vegetable or rice,” Amarjeet Sinha, a senior education official, told the BBC.

Bihar Chief Minister Nitish Kumar called an emergency meeting and ordered a team of forensic experts to the school.

Bihar is one of India’s poorest and most populous states. There are fears the number of dead could rise as some of the children, all below the age of 12, are critically ill.