Washington Post also saying two shooters: http://www.washingtonpost.com/local/police-search-for-active-shooter-on-grounds-of-washington-navy-yard-in-southeast-dc/2013/09/16/b1d72b9a-1ecb-11e3-b7d1-7153ad47b549_story.html
Yup. More laws would totally help. I mean, it isn't like the shooter(s) would break the law. DC is totally a gun friendly place, and carrying an AR around is totally legal. Nevermind how legal it is to carry at the Navy Yard.