None of the possibly ricin-tainted letters mailed to President Obama have reached the White House, authorities say. They were intercepted at a remote mail handling facility. Larry Downing /Reuters /Landov hide caption

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Detective Enrique Chavez logs weapons from a gun buyback in Miami. Arizona's new law requires municipalities to re-sell weapons recovered in such programs. Joe Raedle/Getty Images hide caption

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Francine Wheeler, seen here delivering the presidential address alongside her husband, David, urged the Senate to pass gun control legislation. YouTube hide caption

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This AR-15 style weapon was on display in March at the 7th annual Border Security Expo in Phoenix, Ariz. It's among the type of weapons that advocates of new gun laws want to see banned. Joshua Lott /Reuters /Landov hide caption

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A Bushmaster rifle, similar to the type used by Adam Lanza during the shooting at Sandy Hook Elementary School, and some ammunition magazines. The sale and possession of this type of weapon, and high-capacity magazines, will be severely restricted in Connecticut under new legislation. Michelle McLoughlin /Reuters /Landov hide caption

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Chris Colwell, director of emergency medicine at Denver Health, has treated victims from two of the deadliest mass shootings in the U.S. He says he's deeply disturbed by how easy it is to get guns. Barry Gutierrez/for NPR hide caption

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Vice President Biden at a December 2012 meeting of police chiefs on gun control, held in Washington, D.C. Carolyn Kaster/AP hide caption

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President Obama speaks about his gun control agenda before law enforcement officials in Minneapolis on Monday. The president was doing what his aides say he didn't do often enough in his first term: getting outside of Washington to build public support for legislation. Ben Garvin/Getty Images hide caption

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