TODAY | April 16, 2013
>> pete williams following overnight developments in the investigation. pete, good morning. it seems there is no clearer picture as to who may be behind this.
>> i think that's certainly true although there is high hope that they will be able to answer that shortly. they know for certain the attack involved two bombs, but many other packages found on the street were deemed suspicious and destroyed and that took a lot of time last night. there were many packages to check because after the explosions officials say many people simply dropped what they were carrying and ran, leaving their packages behind. there were conflicting accounts whether investigators found two unexploded bombs . this morning a senior law enforcement official says there were no unexploded devices, just the two that went off. several officials say the bombs that went off included shrapnels to multiply the injuries, bebes and ball bearings. investigators are investigating video to see if they can see individuals placing the packages. there is a video from the back carrying two backpacks but it's too soon to know whether that had anything to do with the attack. authorities say there is no suspect in custody but they did talk last night to a 20-year-old saudi man here on a currently active student visa . he had burns and questioned for hours and it's his home that was searched in the boston suburb of revere. they carried away some materials for examination but one official said it's too certain to know one or the other about him, that he might have been an innocent bystander.