Trauma doctor: 'Extra material' added to bombs to maximize injuries

The injuries suffered by bomb victims taken to Mass. General are consistent with those caused by pellets, nails or other sharp objects, the chief of trauma services said at a press conference this morning.

Dr. George Velmahos said several of the patients at his hospital remain sedated and intubated as they recover from emergency surgery.

Dr. Ron Walls, chair of emergency medicine at Brigham and Women's Hospital, says three patients were hit with "small, round projectiles," another with "a collection of nails."