Boston bombs said to be made from pressure cookers packed with shards of metal, nails and ball bearings
Michael Dwyer, Associated Press
BOSTON — The bombs that ripped through the Boston Marathon crowd appear to have been fashioned out of ordinary kitchen pressure cookers, packed with nails and other fiendishly lethal shrapnel, and hidden in duffel bags left on the ground, investigators and others close to the case said Tuesday.
President Barack Obama branded the attack an act of terrorism, whether carried out by a solo bomber or group, and the FBI vowed to "go to the ends of the Earth" to find out who did it.
Scores of victims remained in Boston hospitals, many with grievous injuries, a day after the twin explosions near the marathon's finish line killed three people, wounded more than 170 and reawakened fears of terrorism. A 9-year-old girl and 10-year-old boy were among 17 victims listed in critical condition.
Officials found that the bombs consisted of explosives put in common 1.6-gallon pressure cookers, one containing shards of metal and ball bearings, the other packed with nails, according to a person close to the investigation who spoke on condition of anonymity because the investigation was still going on. Both bombs were stuffed into duffel bags, the person said.
At a news conference, FBI agent Richard DesLauriers, FBI agent in charge in Boston, confirmed that investigators had found pieces of black nylon from a bag or backpack and fragments of BBs and nails, possibly contained in a pressure cooker. He said the items were sent to the FBI for analysis at Quantico, Va.
Pressure-cooker explosives have been used in international terrorism, and have been recommended for lone-wolf operatives by Al-Qaida's branch in Yemen. But information on how to make the bombs is readily found online, and U.S. officials said Americans should not rush to judgment in linking the attack to overseas terrorists.
DesLauriers said that there had been no claim of responsibility for the attack, and that the range of suspects and motives was "wide open."
Throughout the day, he and other law enforcement authorities asked members of the public to come forward with any video or photos from the marathon or anything suspicious they might have witnessed, such as hearing someone express an interest in explosives or a desire to attack the marathon, or seeing someone carrying a dark heavy bag at the race.
"Someone knows who did this," the FBI agent said.
The bombs exploded 10 or more seconds apart, tearing off victims' limbs and spattering streets with blood, instantly turning the festive race into a hellish scene of confusion, horror and heroics.
The blasts killed 8-year-old Martin Richard of Boston, 29-year-old Krystle Campbell of Medford, Mass., and a third victim, identified only as a graduate student at Boston University.
Doctors who treated the wounded corroborated reports that the bombs were packed with shrapnel intended to cause mayhem.
"We've removed BBs and we've removed nails from kids. One of the sickest things for me was just to see nails sticking out of a little girl's body," said Dr. David Mooney, director of the trauma center at Boston Children's Hospital.
At Massachusetts General Hospital, all four amputations performed there were above the knee, with no hope of saving more of the legs, said Dr. George Velmahos, chief of trauma surgery.
"It wasn't a hard decision to make," he said. "We just completed the ugly job that the bomb did."
Obama plans to visit Boston on Thursday to attend an interfaith service in honor of the victims. He has traveled four times to cities reeling from mass violence, most recently in December after the schoolhouse shooting in Newtown, Conn.
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