BOSTON - UPDATE: 12:23 A.M.
More than 140 now reported injured in the blasts.
UPDATE: 10:26 P.M.
Associated Press reports an 8-year-old boy was killed during the blasts.
UPDATE: 8:57 P.M.
Boston police: A third person killed in marathon bombing.
UPDATE 8:52 P.M.
No suspects yet in this investigation.
UPDATE: 8:45 P.M.
FBI has taken charge of Boston Marathon investigation. Area around blasts has been secured by National Guard, treated as crime scene. Random checks of backpacks and other parcels expected around the city of Boston.
UPDATE: 8:35 P.M.
CNN reports 130 injured, 2 killed, and 12 people in critical condition after Boston Marathon attack.
UPDATE: 7:57 P.M
Boston Globe reports the authorities are saying marathon bombings and fire at JFK library likely unrelated.
UPDATE: 7:46 P.M.
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: 7:30 P.M.
From the Boston Globe: Boston Marathon toll rises even higher. More than 120 treated at 7 local hospitals.
UPDATE: 7:11 P.M.
Local ABC Boston affiliate WCVB reporting at least 98 taken to area hospitals.
UPDATE: 6:45 P.M.
House Speaker John Boehner released the following statement on Boston Marathon attack:
"Words cannot begin to express our sorrow for the families who are grieving so suddenly right now. The House of Representatives offers its prayers to the victims and the city of Boston. We also give thanks for the professionals and Good Samaritans who prevented further loss of life. This is a terrible day for all Americans, but we will carry on in the American spirit, and come together with grace and strength."
UPDATE: 6:39 P.M.
Report: Law enforcement official confirm that one of two people killed in today's explosions was eight years old.
UPDATE: 6:16 p.m.
There were 680 runners from Ohio listed on the 2013 Boston Marathon tracking website; 70 of whom listed a Cincinnati address. There were 120 runners who listed Kentucky as their home state.
Another 283 Boston Marathon runners listed Indiana as their home state.
Resource: Online tools to find local runners in Boston Marathon, http://ow.ly/k5Nil
FROM THE SCENE: Local runners share their experience from Boston http://ow.ly/k5NZm
UPDATE: 6:11 P.M.
FBI confirm explosions were a terrorist attack.
UPDATE: 6:08 P.M.
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.
UPDATE: 5:55 P.M.
Obama to speak from the White House Monday evening at approximately 6:10 p.m. about Boston Marathon explosions.
UPDATE: 5:23 P.M.
From FAA: Please note: the FAA has announced a ground stop for Boston Logan airport until further notice.
UPDATE: 5:08 P.M.
A law enforcement official says cellphone service has been shut down in the Boston area to prevent any potential remote detonations of explosives.
Authorities have not identified what caused the explosives that erupted at the finish line of the Boston Marathon. The official was speaking on condition of anonymity because the investigation was ongoing.
The explosions have killed two people and injured at least 23 others.
Link: Founder of Flying Pig expects local marathon to take on new security, http://ow.ly/k5NpA
UPDATE: 4:55 P.M.
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: 4:41 P.M.
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.
Photos: Images from the Boston Marathon http://ow.ly/k5NvN
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: 4:37 P.M.
The Federal Aviation Administration is warning pilots that it has created a no-fly zone over the site of two explosions at the annual Boston marathon.
The agency said in a notice issued Monday about an hour after the explosions that a no-fly zone with a 3.5-mile radius has been created over 811 Boylston Street. The zone is limited to flights under 3,000 feet in altitude, which is lower than most airliners would fly except when taking off or landing.
The notice says the no-fly zone is effective immediately and will remain in effect until further notice. Pilots planning flights were urged to call their local flight service station.
UPDATE: 4:22 P.M.
Intelligence official: 2 more explosive devices found at Boston Marathon; being dismantle.
UPDATE: 4: 18 P.M.
Two bombs exploded near the finish of the Boston Marathon on Monday, killing two people, injuring 22 others and sending authorities rushing to aid wounded spectators, race organizers and police said.
One runner, a Rhode Island state trooper, said he saw at least two dozen people with very serious injuries, including missing limbs.
About two hours after the winners crossed the line, there was a loud explosion on the north side of Boylston Street, just before the photo bridge that marks the finish line. Another explosion could be heard a few seconds later.
The Boston Marathon said that bombs caused the two explosions and that organizers were working with authorities to determine what happened. The Boston Police Department said two people were killed and 23 others injured.
Competitors and race volunteers were crying as they fled the chaos. Bloody spectators were being carried to the medical tent that had been set up to care for fatigued runners. Authorities went onto the course to carry away the injured while stragglers in the 26.2-mile race were rerouted away from the smoking site.
Roupen Bastajian, a 35-year-old state trooper from Greenville, R.I., had just finished the race when they put the heat blanket wrap on him and he heard the first blast.
"I started running toward the blast. And there were people all over the floor," he said. "We started grabbing tourniquets and started tying legs. A lot of people amputated. ... At least 25 to 30 people have at least one leg missing, or an ankle missing, or two legs missing."
A Boston police officer was wheeled from the course with a leg injury that was bleeding.
"There are a lot of people down," said one man, whose bib No. 17528 identified him as Frank Deruyter of North Carolina. He was not injured, but marathon workers were carrying one woman, who did not appear to be a runner, to the medical area as blood gushed from her leg.
Smoke rose from the blasts, fluttering through the national flags lining the route of the world's oldest and most prestigious marathon. TV helicopter footage showed blood staining the pavement in the popular shopping and tourist area known as the Back Bay.
"There are people who are really, really bloody," said Laura McLean, a runner from Toronto, who was in the medical tent being treated for dehydration when she was pulled out to make room for victims of the explosions. "They were pulling them into the medical tent."
Cherie Falgoust was waiting for her husband, who was running the race.
"I was expecting my husband any minute," she said. "I don't know what this building is ... it just blew. Just a big bomb, a loud boom, and then glass everywhere. Something hit my head. I don't know what it was. I just ducked."
Runners who had not finished the race were diverted straight down Commonwealth Avenue and into a family meeting area, according to an emergency plan that had been in place.
Live camera from Boston finish line: