Four wanted criminals, including the kingpin of their gang, were killed in an encounter in south Delhi's Chhatarpur area, police said. Eight Delhi police personnel were also injured in the gunfight that followed at a farmhouse where they were hiding. The police had information about their movement in the area and they launched an operation this morning in which gangster Rajesh Bharti and three of his gang members were gunned down. Their fifth accomplice got injured and was admitted to the hospital.