Below is an excerpt from Time: The bombs that blew up seconds apart at the finish line of one of the world?s most storied races left the streets spattered with blood and glass, three dead, more than 140 wounded and maimed and gaping questions of who chose to attack at the Boston Marathon and why. Federal investigators said no one had claimed responsibility for the devastating attack on one of the city?s most famous civic holidays, Patriots Day. But the blasts raised alarms of another terror attack in the U.S. after the explosions at a public event among crowds of thousands of spectators. President Barack Obama was careful not to use the words ?terror? or ?terrorism? as he spoke at the White House Monday after the deadly bombings, but an administration official said the attack was being treated as an act of terrorism. ?We will find out who did this. We?ll find out why they did this,? the president said. ?Any responsible individuals, any responsible groups, will feel the full weight of justice.?