Fort Stewart mystery: How did this even happen?

On August 6th, just before noon, chaos erupted at Fort Stewart, Georgia — one of the largest Army bases in the country. A 28-year-old logistics sergeant named Quornelius Radford caused harm to five fellow soldiers during a violent incident in an office building on base.
But here's what makes this incident even more disturbing: Soldiers in U.S. bases are not allowed to carry personal weapons inside the barracks. That means, Radford wasn't supposed to have anything like this with him. So where did it come from? How did he get it inside and use it on his own team?