Didn't that Thousand Oaks killer use illegal military automatic weapons to kill the people?
What good do laws do in that situation?
No it doesn't!
A gas leak into the sewers makes a hell of a lot more sense of a string explosions than somebody with a DEW. And I don't see how a DEW could randomly explode cars in Brooklyn because DEWs are normally aircraft mounted and NYC is airspace is so tightly restricted and monitored. It sounds more like an arsonist sticking something in random gas tanks.