The bombings were a "heinous cowardly act," President Obama said this morning, "and given what we now know about what took place, the FBI is investigating it as an act of terrorism." The President also encouraged strength and vigilance: "The American people refuse to be terrorized."
Latest news on how the bombings happened indicate that the explosives were home-made. Via the Associated Press:
A person briefed on the Boston Marathon investigation says the explosives were in 6-liter pressure cookers and placed in black duffel bags.
The person says the explosives were placed on the ground and contained shards of metal, nails and ball bearings. The person spoke on the condition of anonymity because the investigation was ongoing.
Meanwhile, the FBI is continuing its investigation and are searching homes in the Boston area as well as interviewing eyewitnesses who might have any information in connection with the terrorist attacks.
Police, who have already searched an apartment in a Boston suburb in connection with the Boston Marathon bombings, said Tuesday they have no one in custody but are interviewing hundreds of witnesses, examining surveillance tapes and urging the public to turn over photos and videos of the scene of the twin blasts that left three dead and more than 175 people injured.
"This will be a worldwide investigation," FBI special agent Richard Deslauriers said Tuesday. "We will go to the ends of the earth to identify the subject or subjects who are responsible for this despicable crime and we will do everything we can to bring them to justice."
A law enforcement official told USA TODAY the search of a high-rise in Revere is related to a Saudi national viewed by police as a "lead" -- not a suspect -- in the investigation of Monday afternoon's deadly bombings at the race's finish line.
Police, along with FBI and Homeland Security agents, descended on the Water's Edge apartment, removing brown papers bags, trash bags and a duffel bag among other items.
The FBI's investigation is ongoing, and thoughts and prayers go out to the victims' families in their time of need.