When you can play, pull out your Pistols and blast the guy coming down the stairs. Go up the stairs and start blasting at the many guys you can see. When you need to heal, run back downstairs. Heal so you can see if anyone tries to come down after you. They can't shoot on stiars so they'll have to go to the bottm before they can even shoot one bullet. Run around looking for any more guys then heal before entering the next room. Dual Pistols work best here, yet again. Blast away at anything that moves then go up the stairs and heal in this room. You might notice a guy standing by the message board while you're healing. Get rid of him then go back in the room you were just in and grab the AK and kill anyone who tries to stop you from taking it. There are 2 ways to get out of this warehouse. One is easy, the other, not so easy. Going out the back door is easy so do that. Grab the Saab 9x or the Lexus and head to the next destination using these directions if you need to:

Go out the exit and turn right

Go through the intersection

Take a right at the next intersection and cross the bridge

Go straight over the pavements after the bridge and drive down this road

Go through 4 intersections and over a pavement

Keep going until the road ends, then drive into the Depot parking lot

Go in the front door then turn right and follow the guy up the stairs and into the room. Whack him then head into the warehouse part of the building. Go down the stairs and whack the guy just standing there. Run along the right side of the boxes until you turn left or right between some boxes. Take the path to the right and the mission is complete.