A gunman gathered weapons along the way as he progressed with a mass shooting inside a United States navy office building in Washington, DC.  12 people were killed in Aaron Alexis’ rampage.  Eight more people were wounded.

Very little is known about why the 34-year old ex-Naval reservist and civilian subcontractor stormed the headquarters of the Naval Sea Systems Command in the Washington Navy Yard on Monday morning. 

America’s NBC News reports law enforcement officials say they believe Alexis arrived with only a shotgun, which he bought just last week from a gun dealer in Virginia just 20 miles from Washington.

But when he was eventually found dead by law enforcement, he was in possession of the shotgun, plus a handgun, and an AR-15 assault rifle. 

President Barack Obama called it a “cowardly act.”

Mr. Obama said the rampage targeted patriots, military and civilian alike, “men and women who were going to work, doing their job, protecting all of us.”

Alexis was from New York City and still has family there.  He had been treated for some psychological difficulties over the years, including sleep deprivation and depression. 

But he also had run-ins with the law involving firearms.  Alexis was arrested on 4 September 2010 for allegedly discharging a firearm at his Fort Worth, Texas home.  Seattle police arrested him in 2004 for shooting out the tires of a construction worker’s car.  At the time, he described it to police as an anger-fueled “blackout”.  The police report said he attributed his action to trauma he suffering witnessing the 9/11 attacks.