NEW DELHI, Aug. 22 -- One man was killed and three others injured after a dilapidated two-storey building undergoing demolition collapsed in Karol Bagh on Friday morning, police said, adding that the contractor for the project has been arrested. The incident took place around 11.15am at a building on Pyare Lal Road in Regarpura, according to deputy commissioner of police (central) Rohit Rajbir Singh. "According to a preliminary inquiry, the structure was being demolished by a private contractor engaged by its owners. No permission for the demolition had been obtained from the concerned agency," Singh said. To be sure, official said that private owners need permission from municipal authorities before demolishing structures owned by them. Police said the building collapsed while demolition work was underway, trapping labourers at the site. A police team reached the spot after receiving information and, along with Delhi Fire Services (DFS) personnel, launched rescue operations. Four labourers were affected in the incident. One of them, identified as Sheikh Shamshad, in his 20s, succumbed to his injuries. His body was shifted to the mortuary at Lady Hardinge Medical College and Hospital for further proceedings, police said. Another labourer, Mohammmed Ayub, 25, sustained serious injuries, including a head injury and a fracture in his right hand. He was initially taken for treatment and later referred to Dr Ram Manohar Lohia Hospital, where his condition was stated to be critical. According to police, the building owner and the contractor engaged for the demolition were detained, while the contractor, identified as Arun, was arrested....