Killzone 3 Walkthrough - Pyrrhus Evac: Part 2
4Full Walkthrough: http://www.gamefront.com/killzone-3-walkthrough/
Take out the snipers and head for the ladder. At the top, you'll find more sniper ammo. Head around the corner and get down. Look for the two mounted machine guns — one is on the ground on the left, the other is in the building a little to the right, second floor.
With those two guys down, conserve your ammo and wait for snipers to appear in the building across from you. They're your priority. You'll deal with two or three across from you.
More snipers appear in the building to your left, which you just exited. Take them out, then the ones who appear to the far right. You might have to get up higher to deal with them. Keep your head down until you're ready to take your shot.
A few more shots and you'll get the all clear from Rico — now you can shoot down into the general population of Helghast troops. Take your time and line up good shots, as there's a Trophy at stake.
TROPHY: You can get the "Eagle Eye" Trophy here if you fire off an entire clip of sniper rifle ammo, notching a kill with each shot. Take your time and you shouldn't have trouble at all.
As soon as all the Helghast are dead, you'll get a cutscene.
TROPHY: The "Save the Intruders" Trophy unlocks when you finish up the ARC cannon.
Full Walkthrough: http://www.gamefront.com/killzone-3-walkthrough/