The other day at work I was putting a bottle of detergent away when I saw this bright white flash in front of me. Does anyone know what that kind of thing means?

I have seen people at my work before, I've seen a man standing in a doorway several times and a little kid at the counter. There have been massive renovations in the past few mths there but I haven't seen the people since they finished. Do you think the flash and the people are related somehow?