How to complete the quest?

You need to kill 10 Scavs in the underground warehouse on Reserve (under the depot). 
 

Go to Reserve, down to the underground storage warehouse, and kill 10 Scavs.
 

The screenshots below indicate how you can get there.

Small tips for patch 0.15:
1. Take some cheap pistol or other weapon (for example, from dead Scavs) and shoot in all directions from the storage warehouse. You may be lucky and a “script” will work that will attract more NPCs and they will come to you. It doesn't always work, shots are fired without a silencer. The grenade doesn't work

2. In order for the Scavs to appear in the warehouse, you need to go up to the warehouses from time to time - a trigger is triggered and they spawn inside the warehouse. Try to repeat until the task is completed.

Find an underground storage warehouse on the map

Entrance to the Rosreserve storage warehouse

Entrance to the Rosreserve storage warehouse

Entrance at the transshipment and temporary storage station

Entrance at the transshipment and temporary storage station

Entrance near the depot for repair and maintenance of rolling stock

Entrance near the depot for repair and maintenance of rolling stock