My group just died at NWAF to an invisible player who killed us with an attack that sounded like a melee hit hitting metal. It gave me a small shock effect the first time, then a friend was knocked unconscious in a different hanger, I ran to him and tried to bandage, then I heard the metal hit effect again and I died too. The server was "(Public/Veteran) - 1 #3 NSW games.on.net" and we died at approx 2.20pm GMT. He was also running at turbo speed/teleporting and was able to know instantly where we all were while in different buildings.