WASHINGTON (AP) - 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.
The person says law enforcement officials have some of the bomb components but did not yet know what was used to set off the explosives.
President Barack Obama said Tuesday the bombings were an act of terrorism but investigators do not know if they were carried out by an international or domestic organization, or perhaps by a "malevolent individual."
By JIMMY GOLEN
BOSTON (AP) - Massachusetts Gov. Deval Patrick says no unexploded bombs were found at the Boston Marathon. He says the only explosives were the ones that went off Monday.
Three people were killed, including an 8-year-old boy, and more than 150 injured by two explosions just seconds apart near the finish line.
Special Agent in Charge Richard DesLauriers says at a news conference there are no known additional threats.
Police commissioner Ed Davis says it is the most complex crime scene in history of the department.
Authorities are looking for amateur video and photographic evidence that can give clues to who set off the bombs.
Suffolk County District Attorney Daniel Conley says "what occurred in Boston was an act of cowardice."
UPDATE: Feds seek suspects, motive in Boston bombings
BOSTON (AP) - The FBI has served a search warrant on a home in suburban Boston in the investigation into the Boston Marathon bombing attack. Massachusetts State Police confirm that a search warrant related to the investigation was served Monday night in Revere, but they haven't said anything else.
Some investigators were seen leaving the house early this morning, carrying brown paper bags, plastic trash bags and a duffel bag.
Authorities say so far no suspects have been arrested and they don't have a motive. And the FBI is appealing for any video, audio or photos taken by marathon spectators.
Two bombs went off yesterday afternoon as thousands of Boston Marathon runners had yet to cross the finish line. Three people were killed, including an 8-year-old boy. And more than 140 people were injured, with everything from ruptured eardrums to broken bones, to severe limbs.
President Barack Obama was careful not to use the word "terrorism" as he spoke at the White House Monday, but an administration official says the attack is being treated as an act of terrorism. The Pakistani Taliban said today that it had nothing to do with the attack.
NEW: Europe official: Unlikely Boston a suicide bombing
BOSTON (AP) - A European security official with knowledge of the investigation into twin bombings at the finish line of the Boston Marathon says initial evidence indicates they were not detonated by suicide bombers.
The official spoke from the United States on condition of anonymity because he was not authorized to speak about the U.S. investigation. He says, "investigators believe it was not the work of suicide bombers" but it's still too early to know for sure.
The bombs blew up seconds apart Monday at the finish line of one of the world's most storied races, killing at least three people, including an 8-year-old boy, and wounding more than 140 more.
BOSTON (AP) - Doctors at Massachusetts hospitals have been treating those wounded in yesterday's Boston Marathon bombing for everything from ruptured eardrums to lost limbs. The chief of emergency services at Massachusetts General Hospital says, "This is something I've never seen in my 25 years here ... this amount of carnage in the civilian population. This is what we expect from war."
UNDATED (AP) - Security has been stepped up at landmarks, government buildings, transit hubs and sporting events across the U.S. since yesterday's bombing attack at the Boston Marathon. And British police are making sure there's enough security at tomorrow's funeral for former prime minister Margaret Thatcher and the London Marathon on Sunday.