President Obama condemned the attacks at the Boston Marathon on Monday, promising the "full weight of justice" for those responsible for the twin explosions near the finish line of the storied race.
"We still don't know who did this or why, and people shouldn't jump to conclusions before we have all the facts," Obama said from the White House Briefing Room. "But make no mistake: We will get to the bottom of this. ... Any responsible individuals, any responsible groups, will feel the full weight of justice."
Boston authorities have confirmed at least two deaths and dozens of injuries stemming from explosions.
Obama stopped short of labeling the incident a terrorist attack, saying he was waiting for further information from the scene.
He said Americans would unite behind Boston in the wake of the tragedy.
"Boston is a tough and resilient town; so are its people," Obama said. "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."
House Speaker John Boehner, R-Ohio, echoed the president's sentiment, ordering that flags on Capitol Hill be lowered to half staff.
"Words cannot begin to express our sorrow for the families who are grieving so suddenly right now," he said. "The House of Representatives offers its prayers to the victims and the city of Boston. We also give thanks for the professionals and Good Samaritans who prevented further loss of life. This is a terrible day for all Americans, but we will carry on in the American spirit, and come together with grace and strength."