Your radio came alive briefly, letting you hear a broadcast from Marshal Burke, he reported his position to whoever survived the helicopter crash.
- Outside the building, you will a larger campfire with a watchtower overlooking it ahead of you to the left.
- Head over to the tower and climb up the ladder.
- On top of the watch tower you can find a backpack with some more ammo for your sidearm.
- Collect it and head back to the ladder.
- Take the ladder down and then head over to the left, going wide around the camp.
- Go Southwest around the camp and then South until you are past the camp and getting close to the trailer where Marshal Burke has hidden out.
- Take your time approaching the trailer to search for some ammo, there is a big gun battle coming up.
- There is a lot of ammo that can be found on the Eastern side.
- Collect it and then head into the nearby building to trigger a cutscene.