dark-colored bag or backpack. federal law enforcement sources tell cnn the devices were inside pressure cookers and they believe bbs and nails were part of the explosives. important to know that so far nobody has claimed responsibility. the toll of injured up to 183, three more have died, including 8-year-old martin richard, and krystle campbell. president obama will travel to boston on thursday. now we go to chris cuomo live for us in boston. it seems here we are 24 hours more or later and nobody seems to have a real clue who has done this or why. >> reporter: that shouldn't be surprising, piers, these investigations take a very long time to develop, especially starting with being multifactorial, no group claiming responsibility. so much ground to canvas, this is going to be a difficult investigation. i think it's good news that the