The moment the second explosion occurred near the finish line...

The moment the second explosion occurred near the finish line at the 117th Boston Marathon. The bomb blasts took the lives of three victims and injured more than 260 others. (April 15, 2013) Credit: Dan Lampariello/DobsonAgency/Rex

Obama said urged Americans to "say a prayer for Boston" while the federal government responds and provides full resources to the investigation.

"We still do not know who did this or why, and people should not jump to conclusions . . . but make no mistake, we will get to the bottom of this," Obama said. "Any responsible individual, any responsible groups, will feel the full weight of justice."

Obama noted that the explosions near the end of the marathon left multiple people wounded, "some gravely."

The president noted that it is Patriots' Day in Boston, "a day that draws the world to Boston's streets."

Obama said Boston is a "tough and resilient town, and so are its people."

"All Americans stand with the people of Boston," he said.

A Newsday review turned up half a dozen instances of unidentified remains found on LI in the early '90s — a period when the admitted serial killer began committing murders. NewsdayTV’s Shari Einhorn hosts a discussion with Suffolk County District Attorney Ray Tierney and Newsday criminal justice reporter Anthony DeStefano.  Credit: Newsday Studios; News12/ Pool. Photo Credit: Newsday/ James Carbone; Suffolk County District Attorney; North Shore High School

'We treat each of these cases individually' A Newsday review turned up half a dozen instances of unidentified remains found on LI in the early '90s — a period when the admitted serial killer began committing murders. NewsdayTV's Shari Einhorn hosts a discussion with Suffolk County District Attorney Ray Tierney and Newsday criminal justice reporter Anthony DeStefano.

A Newsday review turned up half a dozen instances of unidentified remains found on LI in the early '90s — a period when the admitted serial killer began committing murders. NewsdayTV’s Shari Einhorn hosts a discussion with Suffolk County District Attorney Ray Tierney and Newsday criminal justice reporter Anthony DeStefano.  Credit: Newsday Studios; News12/ Pool. Photo Credit: Newsday/ James Carbone; Suffolk County District Attorney; North Shore High School

'We treat each of these cases individually' A Newsday review turned up half a dozen instances of unidentified remains found on LI in the early '90s — a period when the admitted serial killer began committing murders. NewsdayTV's Shari Einhorn hosts a discussion with Suffolk County District Attorney Ray Tierney and Newsday criminal justice reporter Anthony DeStefano.

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