Five people, including three minors, were killed in Uttar Pradesh’s Agra district on Tuesday, after they fell into a pit dug up for a septic tank, PTI reported quoting the police. The district administration suspected that poisonous gas in the tank led to the deaths.

The incident took place in Pratappura village in Agra when one of the minors fell into the tank while playing, police official Bablu Kumar told the news agency. Two of his brothers, also minors, then entered the tank to save him and got trapped. After the minors’ mother raised an alarm, two more villagers entered the tank but fainted inside it, Agra District Magistrate Prabhu N Singh said, according to The Indian Express.

There were several discrepancies in the names and ages of those killed in reports, with no official confirmation from the police so far.

“The five deceased were digging the tank when mud collapsed into the pit,” Agra District Magistrate Prabhu N Singh said, according to India TV. “One person died on the spot while four others were taken to SN Medical College where they were declared dead on arrival.”

Fatehabad Sub-divisional Magistrate Sumit Singh said the bodies had been sent for an autopsy.

Uttar Pradesh Chief Minister Adityanath expressed grief about the incident, and announced a compensation of Rs 2 lakh each to the family members of the deceased, PTI reported.