BOSTON — The investigation into the deadly Boston Marathon bombing remains “in its infancy,” federal officials said Tuesday, as they sketched out a massive worldwide probe that has yielded reams of evidence but no suspects or motive.
Richard DesLauriers, special agent in charge of the FBI’s Boston division, said investigators have recovered pieces of black nylon believed to be from a backpack or bag that housed the explosive devices.They also recovered fragments of BBs and nails possibly used as shrapnel in a bomb built inside a pressure-cooker or similar device. Officials said pieces of pressure cookers were found at the scene of Monday’s attack.
The BBs and nails acted like shrapnel, spraying victims within a wide range and causing horrible injuries that killed three people, led to many amputations and injured more than 170.
The material recovered at the bomb sites was sent to the FBI laboratory at Quantico where it will be analyzed in an effort to reconstruct the devices. But the FBI and other law enforcement officials offered no quick resolution of a bombing that has shaken the nation.
“Regarding who might be responsible for this event, our investigation is in its infancy,’’ DesLauriers said at an afternoon news conference. “The range of suspects and motives remains wide open.’’
He said the FBI has received more than 2,000 tips, and other officials said agents are analyzing more than 2,000 digital and still images from the scene.
“We are doing this methodically, carefully, yet with a sense of urgency,” DesLauriers said.
On Tuesday, President Obama called the bombing “an act of terrorism’’ and “a heinous and cowardly act.”
“Any time bombs are used to target innocent civilians, it is an act of terror,” a grim-faced Obama said in a brief statement from the White House. He said authorities don’t yet know the motive behind the attack or whether it was the work of a terrorist group or “a malevolent individual.”
The president will travel to Boston on Thursday to speak at an interfaith memorial service for the bombing victims, the White House announced Tuesday afternoon.
Police here have been scouring hours of videotape and thousands of photographs in an effort to learn who detonated the two bombs near the end of the marathon.
Investigators believe the bombs were placed inside pressure cookers, which were filled with metal , according to law enforcement officials, who spoke on condition of anonymity. The official cautioned that investigators do not know how the explosives were detonated.
Pressure cookers would increase the force with which ball bearings and other metal pieces would explode outward. Doctors who briefed the media described seeing such pieces — nails, shrapnel and pellets — in patient’s tissues, indicating that the bombs were packed to inflict the maximum damage.
Ron Walls, chairman of emergency medicine at Brigham and Women’s Hospital, said three victims had small, BB-type objects that had been blown into their flesh by the bombs. One of the three also had about a dozen half-inch nails embedded in his skin. A fourth individual had a single nail lodged in his body.
The objects were “clearly designed to be projectiles and were built into the explosive devices,” he said at a news conference. Michael Zinner, the hospital’s chief of surgery, compared the bombs to improvised explosive devices similar to those used in the Iraq War.
“Almost all the injuries are in the lower extremities. Think of this like an IED,” he said.
Among the dead was an 8-year-old boy, who was identified as Martin Richard, of Boston’s Dorchester neighborhood. He and his family were watching the race near the finish line, an annual ritual for thousands of Boston families. Martin’s mother and one sister were badly injured in the blast.
The boy’s father, Bill Richard, issued a statement asking for privacy and saying: “My dear son Martin has died from injuries sustained in the attack on Boston. My wife and daughter are both recovering from serious injuries.”
Krystle Campbell, of Medford, Mass., was also identified as being among the dead. The third victim has not yet been identified publicly.
Authorities said police are currently processing surveillance footage and and photo evidence as part of the investigation. Even as victims were being transported from the bomb site on Monday afternoon, Police Commissioner Ed Davis said, officers rushed into nearby business establishments to secure video that could provide them with clues.
Davis asked people to submit any photos or videos that they think might be helpful, especially those from the vicinity of the blasts right before or after.
Also Tuesday, authorities clarified the role of a Saudi national injured in the bombing, who had been the subject of intense media speculation. U.S. officials said the man is regarded as a witness, not a suspect. The Saudi, who is at a Boston hospital, is in his 20s and is in the United States on a Saudi scholarship to study at a university in the Boston area.
“My understanding is, he totally cooperated and he is no longer a person of interest,” Sen. Saxby Chambliss of Georgia, the ranking Republican on the Senate Intelligence Committee, told reporters after a two-hour briefing on the attack.
Chambliss and Sen. Diane Feinsten (D-Calif.), the committee chairman, said investigators were still trying to measure the sophistication level of the explosives.
“That’s the one thing that we don’t know, and that would probably lead the investigators in one direction or the other, the domestic versus foreign,” Chambliss said.
A swath of Boston’s normally lively Back Bay neighborhood remained cordoned off by police tape Tuesday morning. Davis said the size of the crime scene around the marathon finish line had been reduced from 15 blocks to about 12 blocks, and would continue to shrink as evidence is processed. He called it “the most complex crime scene we have dealt with in the history of our department.”
The Boston Celtics canceled a basketball game scheduled for Tuesday night, and the president of Emerson College, located just a short walk from the finish line, said the school would close “to provide a day of healing and reflection” for students and staff. Seven Emerson students injured in the bombing were treated and have returned to campus, President Lee Pelton said in a note posted on the school’s Web site.
“Yesterday, terrorism was brought to the city of Boston,” Mayor Thomas Menino said. “This is a tragedy, but Boston is a strong city, a city that can come through this.”
A total of 176 people who were injured in the blasts were transported to hospitals in Boston and as far away as the South Shore, Davis said. The vast majority went to Children’s, Beth Israel Deaconess, Tufts Medical Center, Boston Medical Center, Brigham & Women’s and Massachusetts General, a hospital official in Boston said.
A trauma surgeon at Massachusetts General Hospital told reporters that 29 people were brought to the hospital and many were in critical condition. He said most of the injuries involved metal pieces that had damaged lower extremities. Many victims, he said, underwent leg amputations.
Eight children were treated at Boston’s Children’s Hospital, and all but three were released by Tuesday morning. Two of those who remained — a boy, 10, and a girl, 9 — had leg injuries and were in critical condition, the hospital said. The third, a 2-year-old boy, had a head injury but was reported in good condition.
Medical personnel at other hospitals said many people suffered from shrapnel-type injuries in their legs, though they were uncertain whether the metal pieces were embedded in the bombs or were blast debris.
“We still do not know who did this or why, and people shouldn’t jump to conclusions before we have all the facts,” Obama said Monday. “But make no mistake: We will get to the bottom of this,” and whoever is responsible “will feel the full weight of justice.”
The explosions destroyed an idyllic afternoon ending for the marathon, just as a bulge of runners converged on the finish line, which was marked by a string of colorful flags from countries represented by the racers.
Runners stopped in their tracks, then ran again, heading not for the finish line but for any place that was safe.
“I was two kilometers away,” said Michael Johnstone, 57, a runner from Newton, Mass. “I suddenly noticed people in suits and other clothes on the street going the other way. I thought it was a breakdown in security, but then we were stopped.”
Medical tents erected to treat cramps or dehydration at the finish line were immediately converted into triage centers, with doctors running into blood-spattered streets to assist the wounded. Race volunteers turned into impromptu emergency squads, jumping over tables piled with Gatorade bottles to tend the wounded and using lanyards as tourniquets. A cook from a nearby restaurant tied his apron around the stump of a woman whose leg had been severed.
The bombings came on Patriots’ Day, a state holiday that recalls the first battles of the American Revolution and brings Bostonians together for their world-famous marathon and an early Red Sox game at Fenway Park. The holiday is not connected to the national Patriot Day that marks each Sept. 11 in memory of those killed in the 2001 attacks.
Many Boston shops and schools were closed Monday, and many people who were off from work were out on the city’s streets. The final mile of the race was dedicated this year to victims of December’s school shootings in Newtown, Conn., and some relatives of children who died that day were in attendance.
In Boston, security at the marathon was carefully planned; hundreds of police officers and other emergency workers lined the route. But the 26.2-mile course is by definition open and sprawling, stretching through the city and its neighboring towns. Davis, the police commissioner, said police swept the route for explosives twice, once early in the morning and once about an hour before the first runners crossed the finish line. But he noted that there was “unrestricted access” to the area around the race, suggesting that the bombs could have been brought in after the sweeps.
Deborah Capko, 49, a breast cancer surgeon at the Memorial Sloan-Kettering Cancer Center running in her first Boston Marathon, had just crossed the finish line and taken her first few sips at the water tent when she heard the explosions. “You had little doubt what it was,” she said. “Unfortunately, it brought back all the memories of 9/11.”
Mary Gibson, a Peace Corps employee who traveled from Columbia Heights to run her first Boston Marathon, finished more than half an hour before the detonation and met her parents, aunts and uncles. Gibson ran a personal best of 3 hours, 30 minutes and 56 seconds. Now she is not sure she will return.
“An event like this is the perfect target for someone who wanted to do harm and cause panic,” she said. “Lots of people in one place . . . many out-of-town tourists who really don’t know where they are going. I know this: Marathons in big cities will never be the same.”
Horwitz and Markon reported from Washington; Loeb reported from Boston. David Montgomery and Mary Beth Sheridan in Boston and Carol D. Leonnig, William Branigin, Debbi Wilgoren, Henri Cauvin, Mike DeBonis, Marc Fisher, Kimberly Kindy, Josh White and Mike Wise in Washington contributed to this report.