The CIA spent countless millions of dollars in the 1950s specifically trying to figure out how to do this.
They claim they failed.
Then in the 60s, there was a wave of political assassinations by "lone nuts" such as the country has never been seen before.
Then the "lone nuts" branched out to schools and other public places.
Same pattern every time:
1. Always acting "alone" and with no known social network
2. Vague if not non-existent motivation
3. Before the shooting, they floated around for months with no visible means of support
4. Without any known training, they're often extremely well trained in combat shooting (ex. quick loading of fresh magazines under high stress conditions)
5. They have nothing to say after committing their crimes.
If it's possible to get a programmed killer into a high secure area to eliminate a major public figure, how hard would it be to get them to commit mayhem in an open, public place? I think we get the answer over and over again.