They said a terrorist present inside the house opened fire on law enforcement personnel.Muhammad Tariq alias Khalid - the main handler of the suicide bombing at the Koocha Risaldar mosque - Abdul Wajid, and Muzaffar Shah were killed in the return fire, Dawn newspaper reported, quoting an official.In the exchange of fire, the three terrorists were killed while four others, including two handlers, managed to escape, the official said.The police said the terrorist group was also involved in the killing of Sikh hakeem medicine practitioner Sardar Satnam Singh in September last year.