WASHINGTON (AP) President Barack Obama, responding to the explosions at the Boston Marathon, says the United States does not know "who did this or why" but vowed that whoever is responsible "will feel the full weight of justice."
He said: "We will find out who did this and we will hold them accountable."
Obama made his remarks Monday evening from the White House about three hours after two explosions detonated near the marathon's finish line. At least two people were killed and 50 injured in the blasts.
Obama has been in touch with federal law enforcement and Massachusetts officials in the aftermath of the explosions.
The Secret Service reacted cautiously to the blasts, expanding the security perimeter around the White House.
Lawmakers suggest terrorism involved in Boston
WASHINGTON (AP) With little official information to guide them, members of Congress strongly suggested on Monday that the deadly Boston Marathon explosions were acts of terrorism and vowed to bring anyone responsible to justice.
"My understanding is that it's a terrorist incident," said Sen. Dianne Feinstein, a California Democrat who chairs the Senate Intelligence Committee.
She told reporters she had been in contact with U.S. intelligence agencies and they reported no advance warning that "there was an attack on the way."
Two other members of the panel, Sens. Susan Collins, R-Maine, and Angus King, I-Maine, said that based on initial press reports that "multiple improvised explosive devices may have been involved at this high profile national event bear the hallmarks of a terrorist attack."
The remarks made by the three lawmakers stood in contrast to President Barack Obama's own brief statement at the White House, where he made no mention of terrorists or terrorism as a possible cause of the bombings.
Majority Leader Harry Reid said on the Senate floor that Obama had spoken with officials in Massachusetts and "pledged every federal resource available ...to bring justice to the perpetrators ..."
House Democratic Leader Nancy Pelosi said "we will ensure that justice will be done" as the casualty toll mounted in explosions blamed for at least two deaths and dozens of injuries.
Lawmakers in both houses marked the bombings with moments of silence.
Reid led the Senate in a brief pause, and officials said Speaker John Boehner intended to do the same when the House convened later Monday.
In a written statement, Boehner said: "This is a terrible day for all Americans, but we will carry on in the American spirit, and come together with grace and strength."
Good afternoon, everybody. Earlier today, I was briefed by my homeland security team on the events in Boston. We're continuing to monitor and respond to the situation as it unfolds. And I've directed the full resources of the federal government to help state and local authorities protect our people, increase security around the United States as necessary, and investigate what happened.
The American people will say a prayer for Boston tonight. And Michelle and I send our deepest thoughts and prayers to the families of the victims in the wake of this senseless loss.
We don't yet have all the answers. But we do know that multiple people have been wounded, some gravely, in explosions at the Boston Marathon.
I've spoken to FBI Director Mueller and Secretary of Homeland Security Napolitano, and they're mobilizing the appropriate resources to investigate and to respond.
I've updated leaders of Congress in both parties, and we reaffirmed that on days like this there are no Republicans or Democrats we are Americans, united in concern for our fellow citizens.
I've also spoken with Gov. Patrick and Mayor Menino, and made it clear that they have every single federal resource necessary to care for the victims and counsel the families. And above all, I made clear to them that all Americans stand with the people of Boston.
Boston police, firefighters and first responders as well as the National Guard responded heroically, and continue to do so as we speak. It's a reminder that so many Americans serve and sacrifice on our behalf every single day, without regard to their own safety, in dangerous and difficult circumstances. And we salute all those who assisted in responding so quickly and professionally to this tragedy.
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. Any responsible individuals, any responsible groups will feel the full weight of justice.
Today is a holiday in Massachusetts Patriots' Day. It's a day that celebrates the free and fiercely independent spirit that this great American city of Boston has reflected from the earliest days of our nation. And it's a day that draws the world to Boston's streets in a spirit of friendly competition. Boston is a tough and resilient town. So are its people. I'm supremely confident that Bostonians will pull together, take care of each other, and move forward as one proud city. And as they do, the American people will be with them every single step of the way.
You should anticipate that as we get more information, our teams will provide you briefings. We're still in the investigation stage at this point. But I just want to reiterate we will find out who did this and we will hold them accountable.
Thank you very much.
Copyright 2013 The Associated Press