Strange light anomaly

id say i was 15-16 years old 1998-1999, and one day I decided to meet up with a friend at his house. The friend lives pretty far so I do not know his area really well. After the initial greeting, we decided to hang out with other friends.

Once we met up with the others, we headed towards what seemed to be a abandoned steel shelter,

possibly world war era. I thought the shelter was a parking garage for small private aeroplane.
Anyways I noticed the shelter was barricaded and locked, but one of the boys managed to unlock the only door to the shelter. Once inside it was absolutely dark, no light/light switch, we could not see how big the shelter was from the inside, there was no light coming through at all. Only sunlight visible was where the door was (the sunlight did not get far) and a little square window on the wall high up in the middle of the wall where the door is. I noticed near the door, newspaper cut outs with black and white photos, I can not remember the exact date of them newspaper now, but I'm guessing 50-55 years before. (1945-1950).
At one point there was only me and my friend in the shelter, standing where the sunlight could touch. My friend picked up what i though was a paperclip, and twisted it, to make it a straight flattened. My friend put his hand up and flicked the paperclip very hard. I do not know why I even bothered to look where the paperclip would land since its so dark, but I did. And as I was looking and expecting to hear it land, I saw a sharp light for a fraction of a second, where the paperclip could of traveled. The light seemed to be really long and thin almost 3 times the size of the paperclip itself and on one side of the light I saw a face, to best describe the face then I would say it looked like the face Mr Bean drew, when he ruined the painting in the movie, MR BEAN DISASTER MOVIE, but not as cartoony. Just feets away to where the paperclip could of traveled was the little window that I mentioned earlier higher up in the wall, but sill I did not see any rays that went far enough to hit the paperclip.

 I looked at my friend and he seemed shocked too, but he then quickly reached a paperclip on the ground near one of his feet, that seemed to be twisted and flatten out. He remarked saying the flick went badly wrong.
After that I went outside and never talked about this again.
I did try to reason it by logic.. But to this day I cannot explain what I saw that day