President Barack Obama says America’s Federal Bureau of Investigation is investigating the bomb attacks at the Boston Marathon. President Obama called the bombings “an act of terrorism,” and a "heinous and cowardly act." But he said officials do not yet know who carried out the attack or why. FBI officials say the investigation will be worldwide. The explosions killed three people and wounded more than 170 others. The Learning English program “As It Is” will have a special report on the Boston bombings at 22:30 UTC Tuesday.