Three Killed, 141 Injured In Boston Marathon Terror Strike

Also, a Saudi national with a leg wound was under guard at a Boston hospital in connection with the bombings, but investigators cannot say he is involved at this time and he is not in custody, a law enforcement official said.

Authorities in Boston found at least one other explosive device that they were dismantling, Davis said.

In a television address President Barack Obama pledged the full resources of the federal government in helping Boston and in investigating the bombings and said those responsible would feel the "full weight of justice."

"The American people will say a prayer for Boston tonight," he said. The president cautioned that authorities were still investigating and that people should not jump to any conclusions before all of the facts are learned.

"But make no mistake," Obama said. "We will get to the bottom of this and we will find out who did this. We'll find out why they did this and we will hold them accountable."

The blast came on Patriots Day, Obama noted, which is a state holiday in Massachusetts that celebrates the beginning of the American Revolution.

Obama stopped short of calling the incident an act of terrorism. Federal authorities are classifying the bombings as a terrorist attack, CNN reported citing a federal law enforcement official.

But it's not clear whether the origin was domestic or foreign, the official said

A federal law enforcement official told CNN that both bombs were small, and initial tests showed no C-4 or other high-grade explosive material, suggesting that the packages used in the attack were crude explosive devices.

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