First time posting here again after a few years.

My one and only encounter with what I believe was a supernatural entity, or my only supernatural experience was back when I was stationed in the Guantanamo naval base. Working the night shift on patrol and we decided to go exploring the underground bunkers. We reached a room right on a "T" intersection and the three of us heard something like a sigh or maybe a gasp seemingly right in front of us. We. Booked. It. We were military police so we had our duty belts but I don't think me nor the other two guys could have sprinted any faster. The room itself had a super old bunk bed and maybe a chair. The lights are always on in those tunnels, so we knew for sure no one was there but us. 

Once I got back to the barracks after that shift was over at 6 am, I couldn't sleep for a few hours.