Metal gear solid game

Hello,I am playing metal gear solid game. I really like it. But I am stuck somewhere in the game. After beating Liquid Snake in Hind D on the roof of communicaion tower B, Otacon comes and tells me that the elevaor has mysteriously started and that I should board it. But after boarding it, he tells me that four soldiers wearing stealth camouflage suits are with me. But whenever I try to use any weapon, the soldiers get knocked out and then again start shooting at me. What am I to do to kill the soldiers? Please help.