Srinagar:Four Lashker-e-Toiba (LeT) militants were killed by security forces in an encounter which ensued during a Cordon and Search Operation (CASO) in south Kashmir district of Shopian, a police spokesman said on Monday.Three militants have been identified as Amir Shafi Mir aka Abu Qasim,Rayees Ah Bhatt & Aqib Ah Malik.