We will find the Boston culprits, hold them accountable: Obama

Reacting strongly to the incidents of three explosions that rocked Boston, US President Barack Obama has affirmed that his administration will find out the perpetrators and hold them accountable for the act.

The President, however, sought to refrain from jumping into any conclusion about the nature of the explosions.

"We still do not know who did this and 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," Obama said in an statement, some three hours after the blasts.

"We will find out who did this (and) why they did this. Any responsible individuals, any responsible groups will feel the full weight of justice," a grim but determined-looking Obama said in his White House statement to the press.

The President said he has spoken to the Boston Mayor and the Massachusetts Governor soon after he was notified and briefed about the happenings by his national security team.

"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," the US President said.

Obama said he and his administration are continuing to monitor and respond to the situation as it unfolds.

"I've directed the full resources of the federal government to help state and local authorities protect our people, increase security around the US as necessary, and investigate what happened," he said.

The President said he has spoken to the FBI Director and Secretary of Homeland Security, besides other top officials of his national security team.

"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," he said.

The President also prayed for the victims on the behalf of himself and the First Lady Michelle Obama.

"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.

"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," Obama said.