Sounds like NATO GLADIO 2.0 stuff. They did these things as shootings non-stop in the US during the 2010s, led by DHS and a lot of British intelligence entities.

I can’t be sure about these German incidents without doing my own investigation, but having dug into the 2010s US mass shootings and read the DHS HSEEP manual, I assure you the authorities in the West have the means, motive, and opportunity to stage large scale disaster drills that they then simply allow the media to cover as real events.