(FOX NEWS) The FBI and state and local police are intensifying their probe into Monday's bombing at the finish line of the Boston Marathon, vowing a "worldwide investigation" and appealing to the public for tips and cellphone pictures that might yield clues about who was behind the horrific attack branded by President Obama as an act of terrorism.
No suspects have been named, but new details are slowly emerging in the attack, which killed three and injured at least 176. Two bombs went off just before 3 p.m., shattering a festive atmosphere several hours after the legendary race began on the city's 238th annual Patriots' Day. An 8-year-old boy was among the dead and several runners and spectators suffered severe injuries, including severed limbs as the bombs sent shrapnel flying.
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"This will be a worldwide investigation," Special Agent-in-Charge of the FBI's Boston Field Office Richard DesLauriers said at a Tuesday morning news conference, adding that investigators will go "wherever the leads take us."