You have a time limit, so get a move on! Here are the directions to get to the next destination:

When you start, turn right out of the gate

Go through the next intersection

When the road ends, turn right and over the bridge

Turn left at the next turn

Go through the next 4 lights

Go through the next intersection

Go through the next set of lights

Stay left when a fork in the road comes up

Go either way around the second fork in the road

Turn right after the second fork in the road

Turn left

When you have to turn, turn left

Stay right at the next fork in the road

Turn left, then right

Turn left

The next left is blocked, so take the second left

Turn left when you have to turn

Turn left again

A good idea at this point, is to steal an Ambulance(but NOT a Firetruck because it's slower) and drive through the smoke while running down any bad guy that you can. Don't hit any vehicles though, because they'll slow you down, allowing enemies to bust up your ride easily. Stay on the sidewalk when going past them. When you get to the other end of the road, pull a skid to the left and get out of the busted-up Ambulance. Kill any bad guys that you can see then steal any AK-47 that they might have dropped. Now make your way back through the smoke after healing yourself. Use the AK if you got one, and blast the rest of the bad guys while making your way back to where you "borrowed" the Ambulance. If you need ammo, use the guns that the bad guys or killed you ran over dropped. If you run low on health, grab one of the many Lexus' around here and try to run down the last few nutters. When they're all dead, the mission is complete.