KATHMANDU: An unidentified gang on Thursday night stabbed a night watchman to death at Gongabu in Kathmandu. According to the Metropolitan Police Sector in Maharajgunj, Durga Bahadur Roka (32), hailing from Sunarpani-8 of Ramechhap was killed at around 2 am. He was appointed as a night watchman for an under-construction house. Police said a massive search is on to nab the assailants .