黑料社

BOSTON鈥擳he 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 鈥済o to the ends of the Earth鈥� 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 finish line of the world鈥檚 oldest and most prestigious marathon killed three people, wounded more than 170 and reawakened fears of terrorism in the US. 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 (6-liter) pressure cookers, one containing shards of metal and ball bearings, the other packed with nails, and both stuffed into duffel bags, said a source close to the investigation who spoke on condition of anonymity because the investigation was still going on.

Pieces of black nylon

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 in Virginia.

DesLauriers said that there had been no claim of responsibility for the attack, and that the range of suspects and motives was 鈥渨ide open.鈥�

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.

鈥淪omeone knows who did this,鈥� the FBI agent said.

FBI agents searched an apartment in the Boston suburb of Revere. According to one law enforcement official, the tenant had been tackled by a bystander, then police, as he ran from the scene of the explosions. But the man may simply have been running away to protect himself, said the official, who spoke on condition of anonymity because he wasn鈥檛 authorized to release details of the investigation.

The bombs exploded 10 or more seconds apart, tearing off victims鈥� 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 Massachusetts, and a third victim whose name has not been released.

Graduate student 3rd victim

Boston University said a graduate student at the school was the third victim. In a statement late Tuesday afternoon, the school said it was not releasing the name or any other information about the student, pending permission from the family.

The statement said the student was with two friends who were watching the race at the finish line, not far from the university鈥檚 campus. One of the friends, also a grad student at the university, was injured and is at Boston Medical Center in stable condition.

Doctors who treated the wounded corroborated reports that the bombs were packed with shrapnel intended to cause mayhem.

鈥淥ne of the sickest things for me was just to see nails sticking out of a little girl鈥檚 body,鈥� said Dr. David Mooney, director of the trauma center at Boston Children鈥檚 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.

鈥淚t wasn鈥檛 a hard decision to make,鈥� he said. 鈥淲e just completed the ugly job that the bomb did.鈥�

Security stepped up

In the wake of the attack, security was stepped up around the White House and across the US Police massed at federal buildings and transit centers in Washington, critical response teams deployed in New York City, and security officers with bomb-sniffing dogs spread through Chicago鈥檚 Union Station.

Homeland Security Secretary Janet Napolitano urged Americans 鈥渢o be vigilant and to listen to directions from state and local officials.鈥� But she said there was no evidence the bombings were part of a wider plot.

Pressure-cooker explosives have been used in Afghanistan, India, Nepal and Pakistan, according to a July 2010 intelligence report by the FBI and the Homeland Security Department. One of the three devices used in the May 2010 Times Square attempted bombing was a pressure cooker, the report said.

Investigators said they have not yet determined what was used to set off the Boston explosives. Typically, these bombs have an initiator, switch and explosive charge, according to a 2004 warning from Homeland Security.

鈥淲e will go to the ends of the Earth to identify the subject or subjects who are responsible for this despicable crime, and we will do everything we can to bring them to justice,鈥� the FBI鈥檚 DesLauriers said.

Pressure-cooker explosives have been used in international terrorism, and have been recommended for lone-wolf operatives by Al-Qaida鈥檚 branch in Yemen. But information on how to make the bombs is readily found online, and US officials said Americans should not rush to judgment in linking the attack to overseas terrorists.

Pakistan Taliban denies

The Pakistani Taliban, which claimed responsibility for the 2010 attempt in Times Square, has denied any part in the Boston Marathon attack.

Al-Qaida鈥檚 branch in Yemen gave a detailed description of how to make a bomb using a pressure cooker in a 2010 issue of Inspire, its English-language online publication aimed at would-be terrorists acting alone.

In a chapter titled 鈥淢ake a bomb in the kitchen of your mom,鈥� it says 鈥渢he pressurized cooker is the most effective method鈥� for making a simple bomb, and it provides directions.

Naser Jason Abdo, a former U.S. soldier, was sentenced to life in prison last year after being convicted of planning to use a pair of bombs made from pressure cookers in an attack on a Texas restaurant frequented by soldiers from nearby Fort Hood. He was found with the Inspire article.

Investigators are combing surveillance tapes and pictures from the Boston attack and appealing to the public to turn over personal photos and video that might yield clues.

鈥淭his is probably one of the most photographed areas in the country yesterday,鈥� said Boston Police Commissioner Edward Davis. He said two security sweeps of the marathon route had been conducted before the bombing.

Boston police and firefighter unions announced a $50,000 reward for information leading to arrests.

Clueless

Obama said officials do not know who carried out the attack or why鈥斺�漺hether it was planned and executed by a terrorist organization, foreign or domestic, or was the act of a malevolent individual.鈥�

But he said 鈥渁ny time bombs are used to target innocent civilians, it is an act of terror.鈥� And he declared: 鈥淭he American people refuse to be terrorized.鈥�

Obama plans to travel to Boston on Thursday for an interfaith service, Massachusetts Gov. Deval Patrick said.鈥�Eileen Sullivan