We were camping near one of the coastal Civil War forts along the Atlantic Coast, and decided to take a stroll inside after dark. We weren't supposed to, but it was a beautiful night with a full moon. We meant no harm to the place, merely sitting down not far inside the entrance and watching. There were four of us. It was July, warm and humid.
After a half hour, we started getting pretty tired; it was after midnight. So we headed down the sidewalk inside, ready to leave. On an impulse, I mentioned that we hadn't even been inside one the many cannon rooms, not a single dark place out of the bright moonlight.
I veered into one of the rooms, about four paces inside. The dark room grew brighter, the light flooding across the floor but not reaching the far wall, about 12 feet ahead of me. I can remember wondering, "Why can I see every detail of the floor?" Nothing could do that, unless some bright comet behind me was lighting up the sky.
I spun around and said, "What the hell was that?" Total darkness. My teenager stood in the doorway, completely speechless. He was covered with goose bumps and cold air. To this day, he has a difficult time describing it.
My wife was eight feet away from him on the outer sidewalk, and stepped over to him and felt the cold air. Better yet, she got a good look at what happened. A "cloud of light" about three feet long had zoomed down out of a nearby tree, into the entrance of the room, almost striking my son. Seconds later it zipped back out. It lit up about 3 feet of ground. She said the light resembled many pieces of a broken mirror. It lasted about 3 seconds, total.
My other son was eight feet farther up the sidewalk, and had his back to the light. However, it spread light across the sidewalk and grass so bright, he thought someone had lit a flare.
If I'd been by myself, I would have thought it was a fainting spell, or something. But all four of us were chattering about it. The light had a very playful, mischievous feel to it, no threat at all. The four of us trudged back to our tent in silence, puzzled and mystified by the whole thing.
Someone more knowledgeable later told us it might have been an "elemental", a non-human life form. I don't know. But four hours later, we had a terrific rain storm with lightning, and our tents were blown down. It was quite a night.