BOSTON Two powerful bombs exploded near the finish line of the Boston Marathon on Monday afternoon, killing three people, including a child, injuring more than 140, and transforming one of the city's most cherished rites of spring from a scene of cheers and sweaty triumph to one of screams, bloody carnage and death.
About three-quarters of the 23,000 runners who participated in the race had already crossed the finish line when a bomb that had apparently been placed in a garbage can exploded in a haze of smoke amid a crowd of spectators on Boylston Street, just off Copley Square in the heart of the city. It was around 2:50 p.m., more than four hours after the race had started, officials said. Within seconds, another bomb exploded several hundred feet away.
Pandemonium erupted as panicked runners and spectators scattered, and rescue workers rushed in to care for the injured, some of whom had lost their legs in the blast, witnesses said. One of the people killed was an 8-year-old, the Associated Press reported.
The reverberations were felt far outside the city, with officials in Washington heightening security on public transit and shutting down streets near the White House. Pennsylvania Avenue was cordoned off by the Secret Service in what one official described as "an abundance of caution."
In New York, the Police Department said it was stepping up security at hotels and other prominent locations in the city until more is learned about the explosion.
"The first one went off, I thought it was a big celebratory thing, and I just kept going," recalled Jarrett Sylvester, 26, a marathon runner from east Boston, who said it sounded like a cannon blast. "And then the second one went off, and I saw debris fly in the air. And I realized it was a bomb at that point. And I just took off and ran in the complete opposite direction."
In the chaotic hours after the explosions, there were reports of at least two other devices found nearby. Police officials said at least one was blown up in a controlled explosion.
At their final briefing Monday night, officials said that the FBI had taken over the investigation. Richard DesLauriers, the special agent in charge of the Boston office, called it "a criminal investigation that is a potential terrorist investigation." But they offered no information on what they had found or what they were investigating except to say that they were bringing "very substantial federal resources" to bear.
It was unclear Monday evening who might be responsible for the blast. Although investigators confirmed that they were speaking to a Saudi citizen, several law enforcement officials took pains to note that no one was in custody.
While the authorities have not arrested the Saudi man, he has remained at a hospital under close supervision by law enforcement authorities, according to a senior law enforcement official.
By Monday night, authorities were acting on the belief that there had been only two explosive devices that had been laid. As a precaution, authorities had blown up several bags which they believed were likely left by marathon runners that were on the streets near the attacks.
The explosive devices used in the attacks on Monday were similar in size to the device used in the 1996 attack at the Centennial Olympic Park bombing in Atlanta but were not nearly as large as the one used in the 1995 attack in Oklahoma City.
In the Atlanta attack, a pipe bomb was detonated near pedestrians, killing two and injuring more than 100 similar numbers to Monday's attack. The attack in Oklahoma City was far larger because the perpetrator packed a truck with thousands of pounds of explosives and the device went on to destroy or damage hundreds of buildings and kill more than 150 people.
The attack on Monday occurred in areas that had been largely cleared of vehicles for the marathon.
Some law enforcement officials noted that the blasts came at the start of a week that has sometimes been seen as significant for radical American anti-government groups: It was the April 15 deadline for filing taxes, and in Massachusetts it was Patriots' Day.
It is also a week that has seen attacks in the past: April 19 is the anniversary of the deadly 1993 fire near Waco, Texas, that ended a 51-day standoff and left 80 members of a religious group called the Branch Davidians dead. April 19 is also the anniversary of the 1995 bombing of the Alfred P. Murrah Federal Building in Oklahoma City, which prosecutors said was conceived in part as a response to the Waco raid.
President Barack Obama, speaking at the White House, vowed to bring those responsible for the blast to justice.
"We will find who did this, and we will find out why they did this. Any responsible individuals, any responsible groups, will feel the full weight of justice," he said.
Police closed down a 15-block radius around the blast site, and some transit stops were closed. Landings were briefly halted at Boston Logan International Airport, and the Boston Symphony Orchestra canceled its Monday night concert. A Boston Celtics game scheduled for today was canceled as well.
Boston Police Commissioner Ed Davis urged people to stay off the streets.
It had begun as a perfect day for the Boston Marathon, one of running's most storied events, with blue skies and temperatures just shy of 50 degrees. More than 23,000 runners started the race, which typically draws half a million spectators.
And long after the world-class runners had finished the men's race was won by Lelisa Desisa Benti of Ethiopia, who finished it in 2 hours, 10 minutes and 22 seconds; Rita Jeptoo of Kenya won the women's race in 2:26:25 the sidewalks of Boston's Back Bay were still thick with spectators cheering on friends and relatives as they loped, exhausted, toward the finish line.
Stephanie Grammel, 26, from nearby Medford was among them, there to watch her little sister run her first marathon.
"All of a sudden there was a loud boom you felt the boom," she said, estimating that she had stood 10 or 15 feet away from the smoky blast, which she said caused bloody injuries throughout the crowd. "There was, at one point, a man with no legs an image I never want to see again."
At least 22 people were taken to Massachusetts General Hospital, said Dr. Alasdair Conn, the hospital's chief of emergency services and several had lost their legs.
"This is like a bomb explosion we hear about in Baghdad or Israel or other tragic points in the world," Conn said, adding that he had never seen such carnage in Boston.
Runners just finishing the grueling race could not believe the scene.
Nico Enriquez, 19, who was running in his first Boston Marathon, had just turned onto the final straightaway on Boylston Street and was looking at the ground when he looked up and saw people running toward him.
"Their faces were just freaked out," he said. "I thought I was hallucinating."
Police faced another problem as they tried to secure the blast scene: Many spectators had dropped their backpacks and bags as they scattered to safety, and investigators had to treat every abandoned bag as a potential bomb.
There were bomb scares at area hotels as well.
At one point in the afternoon, Boston police officials said that they feared that a fire at the John F. Kennedy Presidential Library and Museum could have been related to the marathon bombs, but later they seemed to suggest it was not.