FBI says there is 'a lot of work to do' as authorities comb through evidence and pursue new leads to find who is responsible for deadly twin bombings near Boston Marathon finish line, as a senior White House official tells Fox News the blasts are believed to be an act of terrorism. The blasts left at least 3 dead and at least 144 injured.
- Obama: Those Behind Blasts Will Feel 'Full Weight of Justice' | Secret Service Expands Security at White House
- DR. MANNY: Medical Personnel on Site Saved Countless Lives | Cops Ramp Up Security in Major Cities After Bombings
- British Police Review Security Plans for London Marathon | MAP: Bombing at Boston Marathon Finish Line
- WARNING GRAPHIC IMAGES: Blasts Rock Boston | WATCH: Video Captures Explosions | VIDEO: Blasts Rip Finish
- VIDEOS: What Type of Bomb Caused Blasts? | DR. ABLOW: Why Terrorism Strikes Fear