The guy in the white hat is with the guy in blue, next to him. Both have bags. Guy in blue is clearly talking with guy in white hat in one of the pictures. Backpack bag with guy in white hat has bulge that could easily be pressure cooker. Bag on guy in blue is large duffel, and could easily contain another pressure cooker. Both should be suspects until ruled out by facts, in my law enforcement trained brain.
I was looking at these photos
http://imgur.com/a/sUrnA
I got confused since one of the guys in the white is a white guy with a hat..but as you scroll down you see the guys depicted in the photos here and you can see their face clearly, clearly of arab decent