Death toll three in marathon blasts, Obama vows justice

The FBI took charge of the investigation, classifying it initially as a criminal investigation, but Richard DesLauriers, the agent in charge of the FBI in Boston, said it was a "potential terrorism investigation."
President Barack Obama vowed to bring the perpetrators to justice. Obama stopped short of calling the incident a terrorist attack, but a White House official later said it was "clearly an act of terror."
There were no suspects in custody. DesLauriers encouraged people in Boston "to have a heightened sense of security" and to call a special tip line with any information they may have. He said no piece of information or detail was too small.
Security was increased at a number of other large US cities, including New York and Washington. US aviation authorities briefly instituted a restricted flying zone over Boston.
Boston police commissioner Ed Davis confirmed the higher death toll at a late news conference. The number of injured stood at more than 100, and Davis said many of the victims suffered "serious, serious" injuries.
CNN reported 141 people were injured and that at least 10 limbs were amputated. The bomb scattered ball bearings, which at high speed cause extreme lower limb injuries, CNN said.
There were "simultaneous explosions" at 2:50 pm (1850 GMT) about 50 to 100 metres apart, forcing officials to divert the marathon and clear the area near the finish line where thousands of spectators were watching the end of the race.
Davis declined to comment on reports that as many as five other explosive devices had been planted, but didn't explode.
The winners - Ethiopia's Lelisa Desisa in the mens' race and Rita Jeptoo of Kenya in the women's - had already crossed the finish line when the explosions occurred, but thousands of other runners were still on the course. The race was later stopped as police and fire crews swept the area for possible other explosive devices, authorities said.
About 26,000 runners participated in this year's Boston Marathon, an annual tradition in the Massachusetts city held on Patriot's Day, a public holiday. First run in 1897, it is the world's oldest city marathon and ordinarily is a joyous springtime event.
Television images after the explosion showed some runners falling to the ground when the bombs went off and white smoke rising from an area where spectators were gathered. Police and emergency responders were seen running to evacuate victims and tear down security barriers to reach the injured.
Junye Li, 18, had been watching the race nearby but had entered a bank before the explosions. She said she heard two explosions, saw the windows shake and later saw many people injured.
"When we left the bank we saw two policemen holding a woman, the woman's head was all covered in blood," she said at scene. "We heard a child screaming, everybody screaming, everybody running."
Obama said he had been briefed by the FBI and Department of Homeland Security and said the government would devote its "full resources" to the investigation and to aiding the victims.
"We still do not know who did this or why, and people shouldn't jump to conclusions before we have all the facts. But make no mistake, we will get to the bottom of this and we will find out who did this; we'll find out why they did this," Obama said at the White House. "Any responsible individuals, any responsible groups will feel thefull weight of justice."
The unidentified White House official said in a statement that the evidence pointed to a terrorist attack, even as it remained unclear who was behind the bombings.
"Any event with multiple explosive devices - as this appears to be - is clearly an act of terror, and will be approached as an act of terror," the official said.
"However, we don't yet know who carried out this attack," the statement continued. "A thorough investigation will have to determine whether it was planned and carried out by a terrorist group, foreign or domestic."
Witnesses told US media they had seen many bloody injuries. Local media said some of the injured had suffered severed limbs.
"We heard a big boom like a cannon ... and could see a big plume of smoke," one witness told the Cape Cod Times. "We smelled gunpowder."
Observers described an chaotic scene and photographs showed debris and blood smeared across the sidewalk.
"My ears were ringing, my head's ringing," Globe photographer David Ryan told the newspaper. "Everyone was running like hell."
A third incident at John F Kennedy Library in downtown Boston was "fire related" and no longer appeared tied to the explosions, police later said. Davis had said earlier at the press conference it was being treated as part of the same investigation.
Davis did not provide casualty figures, but police had earlier spoken of two killed and 23 injured. The Boston Globe newspaper later reported more than 100 people hurt.
Other major cities in the eastern US, including New York and Washington, were placed on a heightened security alert after the explosions. Aviation authorities briefly instituted a restricted flying zone over Boston.
Officials told the thousands of runners and spectators to return home or to their hotels and not to gather in crowds.
Bags that had been dropped by fleeing runners and spectators were being investigated as suspicious packages, Davis added. Policed were "methodically" going through the area to check for any suspicious packages, he said.
Condolences and expressions of shock had begun to flow in from around the world.
UN Secretary General Ban Ki-moon said the violence was "all the more appalling for taking place at an event renowned for bringing people together from around the world in a spirit of sportsmanship and harmony."
"I would like to express my deepest condolences to the families of the victims, and to wish those wounded a speedy recovery," he said.