I don't know if this site is credible, but apparently they were holding the door shut.
http://www.thedailysheeple.com/suspi...ng-more_062016
There are groups who want to disarm the American people and they can't do it without an excuse. But who knows if its related to this attack. Although there's alot of red flags, especially when the media focuses on a single incident while shootings happen every single day.