At least three militants were killed during exchange of fire with security forces in South Waziristan Monday, Pakistan Army said. The miscreants attacked the check posts of security forces in Dargai and Tanai. The forces retaliated and killed three militants, Inter Service Public Relations (ISPR) Director General, Maj-Gen Wahid Arshad said. He said that a search operation for the recovery of ten security officials, who were kidnapped a few days back, is under way.