I love history....mostly because so much of it has been forgotten, and you're shocked when you start to stumble across unusual stories.
On a fairly cold day in February of 1780....some Revolutionary War 'vet' (with PTSD obviously), got into a fit and broke into the bedroom of his new boss. He whacked the boss and his wife with a club until they were dead. After that, he burned down the house....with the bosses three grand-kids inside the house. The guy hid out for almost a week before the 'cops' found him. The best that the authorities could dish out was forty lashes, and a hanging. For all practical purposes, this was the first reported mass murder in US history.
In the mid-1930s.....there was this Filipino guy living up in Seattle. He went into a fit over money that was stolen (or he thought it was stolen). Julian Marcelino ended up killing six folks that evening....most of which were just folks on the street that he bumped into. Another fifteen folks were knifed and luckily survived. The cops easily caught him....but then the Seattle crowd went through various phases of declaring Julian insane. Roughly three years later, they ended up putting him up for parole, with the condition that he leave the US. Julian left, and ended up quickly in the Philippines. Curiously, he ended up with the Philippine militia, survived the Bataan Death March, and history indicates that he killed an awful lot of Japanese characters who invaded his island country.
Around 1915, there was this guy from Georgia who got into real estate deals, and found himself screwed at some point. In a fit of rage down in Brunswick Georgia.....he ended up shooting seven guys dead with a newer version automatic shotgun, and wounding 32 other folks. He was shot dead by one of the bystanders who was simply carrying a gun....course, without the concealed permit of today.
The truth is that you can dig around and find hundreds of examples where a guy killed three to a dozen folks in this land between the two coasts. We may have ventured out in the past two decades to some higher numbers.....but we've had people on the rampage for two hundred years. We've found lots of ways to let crazy folks slide by because they were insane. In some cases, we've found ways to lynch guy with barely any evidence because the locals demanded it.
Schools, malls, bars, churches and public places have been popular places for the past two hundred years to murder folks. Nothing new here.....unless you watch the news media and believe everything they say.