President Barack Obama held a press conference on Monday afternoon after two bomb exploded near the finish line of the Boston Marathon.
"We don't 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. 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."
Watch video, uploaded to YouTube, below: