Your stuck with no gear.
Pick up the hand gun and some bullets quickly they are around the area. Note if your out of ammo keep checking areas around the map it's possible that it might re-spawn as well.
Destroy all the infected. Use the explosive ones to take out the riot officers in packs.
Once its over you receive the follow rewards inside the button door.
1. SA-80
2. Backpack XXL
3. All your gear back + food/health
+ Return back to the safe house, via the now opened/hackable door.
This is not a walkthrough. Your post is bad and you should feel bad.