Obama on Boston Blasts

President Obama vowed Monday night to get to the bottom of who is behind a pair of deadly explosions near the finish line of the Boston Marathon, but he warned Americans not to jump to any conclusions.

"We still do not know who did this, or why, and people shouldn't jump to conclusions before we have all the facts," Obama said in a brief statement to reporters hours after the deadly explosions at the iconic American sporting event. "But make no mistake, we will get to the bottom of this."

He added: "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."

While Obama cautioned against jumping to conclusions about the motive for the explosions, a senior administration official said the incident was "clearly an act of terror and will be approached as an act of terror."

"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," said the official, who was not authorized to speak publicly and spoke on the condition of anonymity.