Living a few miles from a fairly busy airport, the flashes from the light warning beacons on low flying aircraft and helicopters can be surprisinngly bright at ground level. I have seen these many times in my own bedroom at night over the years, with the curtains drawn. If you happen to be in exactly the right place, you see just one bright flash which lights up the room, and you don't necessarily hear any aircraft noise. If you didn't know the cause, I think you might well assume the source ot the light must have been inside the room and not outside.
I have even seen these flashes lighting up the ground out of doors in gloomy conditions, when the aircraft was invisible above the cloud cover.