this appears to be is clearly an act of terror and will be approached as an act of terror. 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." now, i can tell you, rachel, that is really the key question here tonight. was this carried out by a terrorist group homegrown, or a foreign terrorist group? and, rachel, the white house just simply does not know. i've heard you sort of discussing this as well. there's still a lot of questions about who is responsible for what happened today in boston. the president was made aware of the events at about 3:00 this afternoon. he was briefed on this situation. as he pointed out in his remarks, he did make phone calls to mayor tom menino as well as governor deval patrick. i have been here really all afternoon. i can tell you moments after those blasts went off in boston, pennsylvania avenue outside of the white house was shutdown. closed to foot traffic.