Posted: 4:37 PM Senate rejects bipartisan plan expanding background checks, major blow to gun control effort .
Updated: 4:56 PM Associated Press is reporting that federal government officials are denying that a suspect in the Boston Marathon bombing is in custody.
Updated: 12:22 PM The U.S. Secret Service says it has intercepted a letter addressed to President Barack Obama that contained a "suspicious substance."
Posted: 11:32 AM Law enforcement officials say a second letter sent to the U.S. Senate has been intercepted and is being tested for poisonous ricin.
Posted: 10:15 PM Family does not want victim's name released.
Posted: 3:10 PM American Airlines flights across the country are grounded because of computer problems.
Posted: 11:56 AM Obama: FBI investigating explosions as `an act of terrorism', orders flags at half-staff
Updated: 11:41 AM President Obama to deliver a statement on the Boston Marathon explosions at 11:30 a.m. EDT.
Updated: 10:54 AM Need to cover a breaking story makes it tough to decide when video is too gory.
Updated: 10:54 AM Extra security at White House, Congress warned to be alert.
Updated: 10:53 AM list of Michigan Boston Marathon runners
Updated: 10:53 AM Pictures and video from the scene of Boston Marathon explosions
