After you chase the woman up the stairs and she gets in the helicopter, turn to your left and go up to the wire that connects to the red-lighted structure. Shoot it at the bottom and some enemies will attack. Shoot and kill them. The farthest enemy will have sniper ammo. Return to the wire that you shot before, get the sniper gun out, crouch, aim, and shoot at the bottom of the wire on the other side. After that, shoot the red-lighted structure a couple times and it will fall over.