The CCTV footages obtained from the hotel show that the girls played in the lawn adjacent to the swimming pool, said a police officer. Around 7.45 pm, she took them to the room.

Soon after, Roy said, he got two phone calls. “The callers said the occupants of room number 601 needed medical help. I immediately went and knocked on the locked door. There was no response. Then I called the police.” The police broke open the door to find her and the children on the bed, unconscious. They were taken to the Max hospital, where the children were declared dead.

Six syringes were recovered from the room, four used and two unused. Rupa had used some kind of anaesthesia — one dose each for her daughters and two for herself.

An officer said Rupa had first called her husband and told him that she was committing suicide and killing the twins as well. It was her husband who called the hotel management.

A statement from the office of the Deputy Commissioner of Police (NorthWest) said: “We have registered a case of murder and attempted suicide. Further investigations are on.”

The couple’s neighbours find the incident hard to believe. Their landlord, Krishnkunj, said: “They have been living here for the past two years. We knew them to be a happy family.”