It isn't the guns

A homeless man sets another man on fire in California by throwing a Molotov cocktail into the victim's car. We have a problem in this country, and it isn't guns. We are in the middle of what Heinlein called "the crazy years."
Making gasoline illegal, restricting high octane gasoline, restricting container size, or requiring a background check in order to buy gasoline, wouldn't fix this any more than the same restriction on guns will fix spree shooting.
It used to be that insane asylums and jails were for keeping dangerous people away from the rest of society. Now we use the jails to lock up people for owning the wrong plant, and we abolished the asylums.