Who was Aaron Alexis?

Monday, 16 Sep 2013 | 7:15 PM ET

CNBC's Bertha Coombs and Diana Olick provide the latest updates on the tragic shooting at a Navy Yard in Washington. Dozens have been injured with 3 in critical but stable condition. Larry Barton, The American College professor, weighs in on the suspected shooter and the possibility of another shooter at large.