peace and rainbows

Doctors at four of Boston’s major hospitals said today that objects appeared to have been intentionally placed into the Boston Marathon bombs to inflict shrapnel wounds on the victims, underscoring the viciousness of an attack that killed three people and injured 176 others, including 17 who are still in critical condition.

The metal fragments found in marathongoers — 20 pieces, or 30 or more in some people — are too uniform, Dr. George Velmahos, trauma chief at Massachusetts General Hospital, said during a morning press conference. They look like pellets or nails, something meant to do harm.

“My opinion is that most of them were in the bomb,” Velmahos said. “I think it’s unlikely they would be so consistent if they were pulled out from the environment.”

Dr. Ron Walls, an emergency physician from Brigham and Woman’s Hospital, also said items were removed from several patients that “clearly were designed to be projectiles that were built into the device.” He described the items as small ball bearings and nails.

Similar comments were also made by doctors at Boston Children’s Hospital and Boston Medical Center.

A federal investigator who responded to the bombings also said authorities have recovered shrapnel that appears to be ball bearings or BBs.

“Anything can cause shrapnel, even a soda can nearby, but it appears this was prepared shrapnel,’’ said the investigator, who insisted on anonymity because he wasn’t authorized to discuss the investigation.

“There appears to be beyond the normal stuff. It looks like the device was prepared with it.” He said agents were collecting evidence and taking it to the Hynes Convention Center.

The Associated Press reported today that a person briefed on the investigation said the two bombs were hidden inside black duffel bags and were made of 6-liter pressure cookers.