NYT:
When the Iraqi units finally did show up, it was with the air of a class outing, cheering and laughing as the Americans blew locks off doors with shotguns. As the morning wore on and the troops came under fire from all directions, another apparent flaw in this strategy became clear as empty apartments became lairs for gunmen who flitted from window to window and killed at least one American soldier, with a shot to the head.
Whether the gunfire was coming from Sunni or Shiite insurgents or militia fighters or some of the Iraqi soldiers who had disappeared into the Gotham-like cityscape, no one could say.
“Who the hell is shooting at us?” shouted Sgt. First Class Marc Biletski, whose platoon was jammed into a small room off an alley that was being swept by a sniper’s bullets. “Who’s shooting at us? Do we know who they are?”
Here.