Let Me Start: New bomb details emerge

Updated
Two men in hazardous materials suits put numbers on the shattered glass and debris as they investigate the scene at the first bombing on Boylston Street in...
Two men in hazardous materials suits put numbers on the shattered glass and debris as they investigate the scene at the first bombing on Boylston Street in...
AP Photo/Elise Amendola

The investigation into who was responsible for Monday’s terror attack at the Boston Marathon is underway. New details about the bombs have begun to emerge: The FBI says they were likely fashioned out of pressure cookers filled with nails and ball bearings and carried in nylon backpacks. But the investigation is in its infancy: No suspects are in custody, no motive is known, and the FBI is asking for tips.

A letter sent to Sen. Roger Wicker (R-MS) tested positive for the deadly toxin ricin. It was intercepted in the field and never reached the U.S. Capitol, and the senator and his office were never in danger.

The Senate will vote today on a flurry of gun safety measures, including the compromise plan to expand background checks offered by Sens. Joe Manchin (D-WV) and Pat Toomey (R-PA) late this afternoon.

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Hardball - Let Me Start

Let Me Start: New bomb details emerge

Updated