When you enter the basement where the hostages are held, notice that there are two or three doors. Equip your Wall Mine and place them in front of the entrances. Do not place the Wall Mines near the entrance to which the turrets are placed. Instead, place them near the main entrance to the basement. Sections of partition of the animal pens will be exposed or seen when the guards enter, and they will through the middle and left entrances. Place the Wall Mines on the partitions enough to be in the middle of the entrance (in length) or in the close range of the door. Once they are set, get ready to cut down three guards. This is the best way to conserve ammunition if you are low. You only need to place two, because the guards will not enter through the third door. This will take out the first wave of guards, leaving you to kill only three of them. You have to do this before you talk to the Chinese hostage, otherwise you will be killed. Note: It is possible to kill Grinko with a well-timed Gas Grenade if you are out of or are low on ammunition.