Two buffaloes also died in the incident in which some other members of the family sustained minor injuries.

The incident occurred in Bhakri village around 2.15 am when Sarjeet, his wife Babita and grandson Nakul were sleeping in a room on the first floor of his house, they said.

A gas leak in their room led to the cylinder explosion, causing the roof to collapse, trapping them under the debris, police said.

According to police, the explosion was so strong that debris also fell on Laxmi and her son, who were sleeping on the roof of a neighbouring house.

The villagers gathered at the spot after the explosion and informed the police. A police team reached the spot and began the rescue operation with the help of a Hydra machine, a senior police officer said.

The officer said that the bodies of Nakul and his grandparents were pulled out of the debris while Laxmi and her child were taken to a hospital, where she died during treatment.

The bodies have been handed over to their respective kin after postmortem on Friday, Dabua Station House Officer Vidya Sagar said.

The cause behind the cylinder blast is yet to ascertained yet and an investigation is underway in the matter, he added.