Calcutta, March 19 :    Calcutta, March 19:  A 10-year-old boy was killed when the elevator door he was said to be leaning against opened suddenly, sending him plummeting three floors down the lift shaft. Witnesses said that around 7 pm, Prakash Mehtani, son of a New Market businessman, was playing in the lobby on the fifth floor of Ambassador Apartments, at 61/A, Park Street. For some reason, the boy decided to lean against the elevator door. Inexplicably, the door slid open, sending the boy tumbling about 45 feet down the shaft. The lift was then on the second floor. Reports said late at night that Prakash may have been electrocuted, as he was found in a tangle of wires on top of the elevator by fire brigade personnel, who rushed to the spot shortly after the incident. Members of the Mehtani family, however, refused to speak to the media on the incident. C.K. Poddar, a neighbour, said that Prakash was a 'cute and bubbly' child and a student of a central Calcutta school. Liftman Ram Singhasan Thakur gave an account of what happened on Monday evening. 'It was around 7.15 pm and I was operating the lift,' he said. 'I was moving up and suddenly. when the lift reached the second floor, there was a thud. The lift came to a halt. I did not realise what had happened. It was only when the fire brigade personnel arrived and rescued me and brought down the boy did the tragedy dawn on me.' The police and fire brigade personnel, however, said that it was still not clear how the boy fell down the elevator shaft. 'We are investigating all aspects, including the theory that the lift door suddenly opened,' said deputy commissioner of police, south, Ranjit Pachnanda. 'Till now, we have no authentic version of what really happened.' At the time of the tragedy, Prakash's father, Deepak Mehtani, was in his New Market shop, while his mother, Meena, was at home with her daughter. Liftman Thakur said Prakash and his friends would often play cricket in the lobby. 'I don't know what happened,' Thakur said. 'But it is a fact that the lift door, especially on the fifth floor, was defective. It is possible that Prakash had dashed against the door, which gave way on impact.' Prakash's friends, with whom he was playing on Monday, were too shocked to speak and were huddled inside their homes after the incident. The police intend to speak to them as well as the elevator manufacturers to get a clearer picture of what had really happened.