Dr. George Velmahos, chief of trauma at Massachusetts General Hospital, told a news conference today that patients were hit by what appeared to be shrapnel packed into the bombs, what he described as "Nails or sharp objects."
"I can't say for certainty, but that's what they look like. [They're] numerous… 10, 20, 30, 40 in their bodies, maybe more," Velmahos said.
Dr. Ron Walls, chair of emergency medicine at Brigham and Women's Hospital, said, "The most common serious injuries are combined lower extremity injuries."
Doctors have said they carried out several amputations.