Taking the KZ2 discussion out of the FEAR 2 thread. :)
But the way the preview phrased it... normal gunfire. It stated that if you ran in guns blazing you may last about thirty seconds. They stressed you would need to make use of the games cover system because gunfire could kill you in two or three good hits.
http://www.gametrailers.com/player/44237.html
Honestly not trying to start anything, just going by various things I've heard/read about the game.