I believe the actual count is 3 legally owned fully autos have been used in any crime since 1934...
To have a license for a fully automatic weapon is an expensive process, that basically requires extensive background checks, lots of money and you agree that the feds can show up at your door at any time and demand to see your weapons or go to jail.
Based on the audio alone its clear the weapon(s) used were fully automatic... whether built that way or converted I don’t know... based on the fact it seems there were bouts of fire, silence and then more bouts of fire, seems to imply the complete unloading of a magazine or clip, a reload, or weapon change, and another ... didn’t sound like a few shots , then a re-aim, a few more automatic shots... etc etc...Almost as if, once the trigger was pulled it could not be stopped until the clip was empty... but that’s just conjecture....
Time will tell what exactly happened, but the odds that this animal was using legal guns is next to nil. Is it possible he had a federal license to own fully automatic weapons? Yes... is it likely? very much not likely.