What happened when they killed me in WoW?

Okay so I was just walking around the outskirts of Crossroads, and my chat box said that the Crossroads were under attack. So I went there and i saw this "Level ???". His name was Skullcandy. He waved at me, then went up to me and just killed me. Then he went back to killing all the NPC's around the city. I went back and he killed me two more times before I just logged out so he couldn't kill me. Who was this and how did he kill me?