"We still do not know who did this or why, and peopleshouldn't jump to conclusions before we have all the facts,"Obama said in a televised statement. "But make no mistake, wewill get to the bottom of this, and we will find out who didthis, we'll find out why they did this."Obama said he has directed the federal government toincrease security around the United States as necessary afterthe explosions.
Two explosions hit the Boston Marathon as runners crossed the finish line on Monday, killing at least two people and wounding 23 more on a day when tens of thousands of people pack the streets to watch one of the world's best known marathons.
The White House does not yet know who planned and carried out explosions at the Boston marathon but is handling the incident as "an act of terror," a White House official said on Monday."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, and a thorough investigation will have to determine whether it was planned and carried out by a terrorist group, foreign or domestic," the official said.
Boston police also reported another explosion at the John F. Kennedy Presidential Library, which is three miles from the marathon's finishing line.
"We are not certain that these incidents are related, but we are treating them as if they are," Boston Police Commissioner Ed Davis told a news conference.
Washington's mayor said on Monday there was no information about any specific threat against targets in the US capital after deadly explosions during the Boston marathon."We have been monitoring the situation in Boston and any possible consequences for the District since shortly after this tragic incident occurred," Mayor Vincent Gray said in a statement. "While at this time there is no information regarding any specific credible threat against targets in our region, we have plans in place to address these types of incidents."
Boston police said two people were killed and over 100 people were reportedly injured in the explosions on the marathon scene.
Davis said that the blasts, apparently some 50-100 meters apart, caused "multiple casualties." He added urged people to stay home or go back to their hotels, and to avoid congregating in large crowds. "People should be calm, but they should understand that this is an ongoing event," he said.
Two high-level US law enforcement officials said one or more bombs were responsible for the explosions.
A fireball rose from behind spectators and a row of flags, video posted on the New York Post website showed. Other pictures showed blood stains on the ground and several people knocked down.
Massachusetts General Hospital was treating 19 victims of the explosion in its emergency room, six of them in critical condition, a spokeswoman said.
Witnesses said two explosions hit as spectators were cheering on people finishing the Boston Marathon, which was first run in 1897.
Reporters in the media center heard two blasts.
Ambulances, fire trucks and dozens of police vehicles converged at the finish line.
US President Barack Obama was notified and directed his administration to provide whatever assistance was necessary, the White House said. Obama was being briefed by Homeland Security Adviser Lisa Monaco and other staff, the White House said.
Massachusetts Governor Deval Patrick told reporters that the president had offered the "full cooperation" of the FBI.
Meanwhile, authorities tightened security in Washington and New York.
"Blood everywhere, victims carried out on stretchers. I saw someone lose their leg, people are crying," the Boston Globe's Steve Silva reported from the scene, the Globe said on Twitter.
Hundreds of thousands of spectators typically line the 26.2 mile (42.19 km) race course, with the heaviest crowds near the finish line. The blasts occurred more than five hours after the start of the race, at a time when most top athletes were off the course but slower amateur marathoners were still running.
The transit agency shut down all service to the area, citing police activity.
Ambulances arrived on the scene within minutes and runners and spectators could be seen crying and consoling each other.
More than 100 people were treated at area hospitals after explosions following the Boston Marathon on Monday, the Boston Globe reported on Twitter.It was unclear what source provided the information that was reported on the Globe's Twitter feed. Reuters could not independently verify that at least 100 people had been injured.