Boston Marathon explosions considered ‘an act of terror’

President Barack Obama said federal and state law enforcement officials are investigating the two blasts at the 117th Boston marathon as acts of terrorism.

Howard Manly | 4/18/2013, noon

Boston Police Commissioner Edward Davis said investigators also gathered a large number of surveillance tapes from businesses in the area and intend to go through the video frame by frame. “This is probably one of the most photographed areas in the country yesterday,” he said.

In his comments on Tuesday, Obama praised the efforts of Boston officials, emergency personnel and what he called heroic Americans who provided aid and comfort to those injured during the aftermath of the blasts.

“The American people refuse to be terrorized,” Obama said. “Because what the world saw yesterday in the aftermath of the explosions were stories of heroism and kindness, and generosity and love.”

Obama cited “exhausted runners who kept running to the nearest hospital to give blood, and those who stayed to tend to the wounded, some tearing off their own clothes to make tourniquets.”

But Obama was clear about the investigation. “In the coming days, we will pursue every effort to get to the bottom of what happened,” Obama said. “And we will continue to remain vigilant.”

Until further notice, Copley Square is an active crime scene, and as such, Boylston Street from Berkley Street to Massachusetts Avenue will be closed to food and vehicle traffic as well as all side streets along Boylston Street from Huntington Avenue to Newbury Street.

The attack appears to have been timed for maximum bloodshed: The four-hour mark is typically a crowded time near the finish line because of the slow-but-steady recreational runners completing the race and because of all the friends and relatives clustered around to cheer them on.

Davis, the police commissioner, said authorities had received “no specific intelligence that anything was going to happen” at the race. On Tuesday, he said that two security sweeps of the route had been conducted before the marathon.

Material from published reports contributed to this article