I don't believe in the paranormal but I did have a weird incident happen when I was 12.
Three friends and I visited our friend's dad's house in Shit-kicker-shit-ville, Arizona (a town divided between an Indian reservation and dilapidated ranches). At the time, we liked to bike/BMX, so we also brought our bikes and road around the shithole. We stumbled across an abandon building, boarded up at every opening, and at least a half a mile away from anything else (we later found out it was a old folks home/medical center).
So being the little delinquents we were, we decided to break in. (Before I describe what happened) The facility, standing at one story, was essentially set up as one long, main hallway, with--at least--40 rooms branching off. We cracked up a board at the front-corner of the place, leading us into the first room on one side of the hall. I went in first (a decision based between me being the bravest and also being the bitch of the group), and stood in this dorm/studio room with the door leading to the hall open.
Now, I may have had some courage, but I was scared shitless as this place was huge and my only idea of the rest of the building was this doorway of complete blackness.
I skimmed the wall--opposite the door--towards the door to see if anything was visible (lights, hobos, ect.). At the angle I was at, if there were lights, I should have seen straight back to the end of the hall. I climbed back out and told everyone there was no way we could explore this death house without flashlights or something.
So we went back to my friend's dad's house, got flash lights, and went back.
This time I climbed in third (out of the four of us).
My two friends called out to me, "What were you talking about, we can see shit, there's lights coming from all the rooms??"
As I made it through the window, I heard this but didn't have a view into the hall. Confused, I walked towards the door, where my friends stood on the other side in the hall, and saw just as they said. Sunlight beaming out of every fucking room down the hall.
It took me .0000001 of a second to book it out of there screaming, as my friends followed. The guy still outside was gone, 100ft ahead of us, spiriting as soon as he heard us screaming. We left our bikes; eventually coming back to get them after we walked back to our friend's dad's house, told him what happened, and he took us back to pick them up.
To this day I have no idea what the fuck happened.