WASHINGTON -- President Barack Obama said authorities don't yet know who is behind the Boston Marathon bombing on Monday, but warned that the perpetrators will be tracked down and "will feel the full weight of justice."
"We don't yet have all the answers, but we do know that multiple people have been wounded, some gravely," Obama said during brief remarks at White House, hours after two explosions at the race finish line caused dozens of injuries and at least two deaths.
While vowing to find out who caused the bombings, Obama urged caution in assigning blame, noticeably avoiding the use of words like "terrorism" or "attack" as he characterized the day's events.
"We still do not know who did this, or why, and people shouldn’t jump to conclusions before we have all the facts," he said. "But make no mistake: we will get to the bottom of this, 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."
A White House official said the president was notified of the explosions just after they took place, around 3 p.m. He was initially briefed by Homeland Security adviser Lisa Monaco and senior White House staff, and later received updates by FBI Director Robert Mueller and Homeland Security Secretary Janet Napolitano.
He also made a number of calls: first to Boston Mayor Tom Menino and Massachusetts Gov. Deval Patrick to "make it clear they have every single resource necessary" to remedy the situation. Then he made calls to congressional leaders in both parties.
"We reaffirmed that on days like this, there are no Republicans or Democrats," Obama said. "We are Americans united in concern for our fellow citizens."
The president said he will provide more information as it becomes available, but for now, the matter is "still in the investigation stage" and people should keep the victims in their thoughts.
"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," he said.
UPDATE: 7:30 p.m. -- Shortly after Obama's remarks, a White House official wasn't as reluctant to characterize the incident as a terrorist attack.
"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."