Coordinates: [712564; 3416087]
Note: On one of the higher floors of the building located south of the Helicopter Hill base camp. Locate interactive ledges in order to reach the upper gallery.
When you find the Alarm siren, use the axe to destroy it (reward: 10 XP).
Coordinates: [712596; 3416035]
Note: On the roof of the hut adjacent to the tower near which Lara took a stand against an enemy attack. Use the ladder or create a rope bridge to get to it.
Destroy the Alarm siren with the axe (reward: 10 XP).
Coordinates: [712589; 3416050]
Note: On the roof of one the metal structures located in the southern area of the town; the best moment to reach it is when you're on your way to Grim's location. Find a small ramp off which you can bounce.
The Alarm siren has been placed by the edge; use the axe to destroy it (reward: 10 XP).
Coordinates: [712602; 3416052]
Note: In the southern part of the town, south-west of the windmill. Start at its foot, then take the path towards the inner gallery.
Turn right and use the axe to destroy the Alarm siren (reward: 150 XP).
Note - there are more alarm sirens in the town, but finding them is not awarded any XP and you don't need to destroy them to complete the location in 100%. Four is enough.