I know these shootings are impossible to stop, but this might be a start that wouldn't hurt:

don't picture their picture in the news
don't publish their manifesto
don't tell their life story
don't make them famous
don't give them the attention they crave.
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He who joyfully marches in rank and file has already earned my contempt. He has been given a large brain by mistake, since for him the spinal cord would suffice.

- Albert Einstein.