So this guy named David Koresh had a compound with a bunch of his followers living there. Long story short, the U.S. government went to the compound to arrest him, there was a stand-off, the feds lobbed some type of incendiary device(s) and a whole bunch of the Davidians died. My opinion is that the government has a habit of using over kill, particularly when dealing with people that have an "unusual" lifestyle.
When ATF tried to serve a search warrant based on reports of illegal weapons, koresh refused entrance and shooting started. Who fired the first shot has always been disputed. Koresh was an @ss willing to let his folks die.