Sri Lanka says the killing of its foreign minister was a "grave setback" for the country's cease-fire, as troops carry out an intensive search for the assassins. Armed forces stopped vehicles and went house-to-house on Saturday in the capital, Colombo, after the government imposed a state of emergency. Officials say Friday's sniper shooting of Foreign Minister Laksham Kadirgamar in Colombo is a blow to reviving the fragile peace initiative between the Tamil Tiger rebels and the government. Military officials say the Tamil Tigers are prime suspects in the assassination of Mr. Kadirgamar, a Tamil and a close advisor to President Chandrika Kumaratunga. The rebels deny involvement in the shooting, but a Sri Lankan spokesman says the government finds their denial hard to accept.