About 17:18 my attention was drawn away from my computer screen by a big orange light in or behind the neighboring town Pirna lighting up the sky for a few seconds. Then something smaller and brighter - a fireball, I suspect - came partly into view for a bit before all the light was gone. A few seconds later the shockwave rumbled past and made even my building make a noise (can't remember what it was, if the wall did it or if the window rattled or something).

Googling didn't turn up anything about it yet, but I did find out that this town has an explosives factory and at least 2 places near that town have fireworks factories.
dieastra, do you know anything?

ETA at 20:24: Google is turning up lots of news by now - it's all over the German news websites. A furnace in a chemical factory (which is 17km from my apartment) in Pirna blew up, one person died, 4 injured.