Assam, Sep 14 (ANI): A grenade blast by two unidentified men in Mangaldoi town of Assam killed one and severely injured four others. The injured were immediately rushed to a nearby hospital. Earlier on Thursday, the security forces had gunned down at least three militants of the United People's Liberation Front (UPLF) in the Hatikhali area of Assam's Dima Hasao District recovering huge cache of arms and ammunitions from them.