Four policemen were killed in Jammu and Kashmir's Sopore town on Saturday when an improvised explosive device or IED went off in a market. The attack was aimed at a patrol unit of the police. The terrorists had planted the remote-controlled IED near a shop in a lane between 'Chotta Bazaar' and 'Bada Bazaar'. It was detonated when the policemen reached the scene while doing their rounds this morning, news agency Press Trust of India reported, quoting officials. Three shops were also destroyed in the massive explosion.