Aaron Alexis, the single suspect in Washington DC Navy Yard Shootings is said to have been under treatment at the Veterans Administration for severe mental problems, including paranoia, hearing voices, and inability to sleep. The Navy did not declare him mentally unfit, since this would have rescinded his security clearance which had been obtained during earlier service in the Navy Reserves. It appears that Alexis was attempting to self-treat his bad temper.
From CNN, it appears that earlier reports that an AR-15 was used in the shootings was wrong. A shotgun and two handguns have been recovered from the scene. The shotgun is believed to have been brought in by the shooter, and the handguns might have bben taken from guards at the Navy Yard. It is suggested that Alexis had rented an AR-15, but returned it sometime prior to the rampage on Monday.
Thus far, the death toll attributed to Alexis is up to 12 Americans.
There of course is clamoring for more gun restrictions nationally, although this shooting occurred in a place with the most restrictive gun laws.