UPDATE - 6:00PM - BOSTON (AP) -- Boston police: At least 3 people killed in marathon bombing.
UPDATE - 5:23PM - WASHINGTON (AP) -- The Navy has sent one of its bomb-disposal units to Boston to assist local authorities as needed in the aftermath of the two explosions near the Boston Marathon's finish line. The blasts killed two and injured more than 100.
The three-member explosive ordnance disposal team based at Naval Station Newport, R.I., was sent to Massachusetts after state officials asked for help. Authorities are investigating the bombings and also are checking other bags and packages that may have been left unattended as terrified crowds races away from the chaos Monday.
The Pentagon said no other active duty military personnel had yet been sent to the scene, although state National Guard troops were there. The Defense Department has not raised the threat level across the nation's military installations.
UPDATE: 4:42PM - CNN is reporting at least 132 were injured in the explosions. At least 17 of the injured are in critical condition and eight of the injured are children.
UPDATE - 3:37PM - Law enforcement official tells NBC News that one of the two people killed in today's explosions was eight-years-old.
UPDATE - 3:35PM -
WASHINGTON (AP) -- President Barack Obama, responding to the explosions at the Boston Marathon, says the United States does not know "who did this or why" but vowed that whoever is responsible "will feel the full weight of justice."
He said: "We will find out who did this and we will hold them accountable."
Obama made his remarks Monday evening from the White House about three hours after two explosions detonated near the marathon's finish line. At least two people were killed and 50 injured in the blasts.
Obama has been in touch with federal law enforcement and Massachusetts officials in the aftermath of the explosions.
The Secret Service reacted cautiously to the blasts, expanding the security perimeter around the White House.
UPDATE - 3:15PM - BOSTON (AP) -- Boston police say no suspect has been taken into custody in connection with the explosions near the finish line of the Boston Marathon.
Police Commissioner Edward Davis also says that the fire at a library a few miles away and more than an hour later doesn't appear to be related to the explosions at the race on Monday. He says the fire may have been caused by an incendiary device.
Authorities say the blasts killed two people and injured at least 73.
Police say it's too early to get into specifics about the nature of devices or whether shrapnel was involved.
Nuclear power plants in Massachusetts and New Hampshire have increased security. The Pilgrim Nuclear Power Station in Plymouth, Mass., and the Seabrook Station in Seabrook, N.H., heightened checks of vehicles, materials and individuals entering the plants.
Pilgrim, about 45 miles south of Boston, was already shut down for refueling when the explosions occurred. Seabrook is about 45 miles north of Boston in Seabrook, N.H.
Eliot Brenner, a spokesman for the Nuclear Regulatory Commission, said federal officials have not ordered changes in security at other U.S. nuclear reactors in the wake of the Boston explosions.
UPDATE - 2:45PM - WASHINGTON (AP) -- Cellphone companies say service is operating in the Boston area, but with heavy traffic following of the explosions at the Boston Marathon.
A law enforcement official, citing an intelligence briefing, said cellphone service had been shut down Monday in the Boston area to prevent any potential remote detonations of explosives.
But officials with Verizon Wireless and Sprint Nextel said there had been no such requests.
Sprint spokeswoman Crystal Davis said: "Minus some mild call blocking on our Boston network due to increased traffic, our service is operating normally."
Two people were killed and scores injured when two explosives detonated near the finish line of the marathon.
Families searching for relatives who ran in the Boston Marathon can call 617-635-4500.
UPDATE - 2:05PM -
BOSTON (AP) -- Boston police say there's been a third explosion in the city, following two blasts near the finish line of the Boston Marathon that killed two people and injured many others.
Police Commissioner Edward Davis says authorities aren't certain that the explosion at the JFK Library was related to the other blasts, but they're treating them as if they are.
David says there are no injuries stemming from the third explosion.
He urged people to stay indoors and not congregate in large groups.
UPDATE - 1:52PM - The New York Post is reporting they have identified a suspect. The Post says the suspect is a Saudi national. The suspect suffered shrapnel wounds and is being guarded in a Boston hospital.
The Post also says that 12 people have been killed and almost 50 people were injured.
UPDATE - 1:48PM - Nightly News has tweeted that the FAA has announced a ground stop for Boston Logan Airport until further notice.
UPDATE - 1:33PM - The New York Post is reporting that police are guarding a suspect in a Boston hospital.
WASHINGTON (AP) -- A senior U.S. intelligence official says two more explosive devices have been found near the scene of the Boston marathon where two bombs detonated earlier.
The official said the new devices were being dismantled.
It was not immediately clear what kind of devices had been found Monday. The official said the first two did appear to be bombs.
The official spoke on condition of anonymity because he was not authorized to discuss the findings publicly.
The official said it was not clear what the motive was or who may have launched the attack.
UPDATE - 1:30PM - NBC is reporting at least 23 injured including some people receiving amputations. Six are severely injured.
UPDATE: (AP) -- Intelligence official: 2 more explosive devices found at Boston Marathon; being dismantled
UPDATE 1:08 P.M.: The Associated Press reports, the Boston Police Department have confirmed two fatalities connected to the explosions.
BOSTON, Mass. (Boston Globe, KRNV & MyNews4.com) -- The Boston Globe is reporting multiple people were injured after two explosions near the Boston Marathon finish line.
The Boston Globe says there were two booms heard inside the Fairmount Copley Plaza Hotel.
Race officials locked down the hotel because of the report.
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