You can google Las Vegas shooting. Short version is 2 idiots shot (execution style) 2 Las Vegas police officers while they were having lunch at a CiCi's Pizza and then went over to a Wal-Mart and killed another person, then killed themselves. They had said something about the "start of the revolution" and had that old flag with the coiled snake "Don't Tread on Me".
Actions like these make me glad I didn't become a police officer in Washington, DC in 1970 and very happy that I visit the Law Enforcement Memorial in DC just about every year in November.