The FBI is taking charge in the criminal investigation of the explosions at the Boston Marathon.
The announcement came Monday night at a news conference in Boston whose participants included Richard DesLauriers, the agent in charge of the FBI in Boston.
Also on Monday night, the FBI said it had set up a phone line for members of the public to call with information about the explosions to contact the law enforcement agency. The call-in number is 1-800-CALL-FBI (1-800-225-5324), prompt (hash)3.
"No piece of information or detail is too small," the FBI said in urging the public to respond.
The FBI said it is seeking information, visual images or details regarding the explosions along the marathon route and elsewhere.
Earlier Monday, Attorney General Eric Holder directed the full resources of the Justice Department be deployed to investigate the bombs that exploded at the near the marathon's finish line.
A department official said Holder had spoken with FBI Director Robert Mueller and with Carmen Ortiz, the U.S. attorney for Massachusetts. The official said Ortiz's office was coordinating the department's response with the FBI and other federal, state and local law enforcement authorities.
The official spoke on condition of anonymity because she was not authorized to speak on the record.
Two bombs exploded, killing three people and injuring many others. A senior U.S. intelligence official said two other explosive devices were found nearby.
Associated Press writer Pete Yost contributed to this report.