UPDATE 4/15/13 @ 10:25 p.m.
BOSTON (AP) -- A person familiar with the situation tells The Associated Press that an 8-year-old-boy has been killed in the explosions near the finish line of the Boston Marathon.
Police say three people were killed in the blasts. They provided no details, but someone who spoke to a friend of the family and spoke to the AP on condition of anonymity to protect the family's privacy confirmed that an 8-year-old boy was among the dead.
The person said the boy's mother and sister were also injured as they waited for his father to finish the race.
The explosions injured more than 170 people, 17 critically.
Police commissioner Ed Davis confirmed the three deaths but provided no details.
The explosions Monday also injured more than 130 people, knocking spectators and at least one runner off their feet.
Some of the victims lost arms and legs. Other injuries included broken bones, shrapnel wounds and ruptured eardrums.
Eight hospitals report that they are treating at least 124 people. Of those, at least 15 are in critical condition.
The injuries ranged from cuts and bruises to amputations. Many victims suffered lower leg injuries and shrapnel wounds. Some suffered ruptured eardrums.
Dr. Richard Wolfe, chief of the department of emergency medicine at Beth Israel Deaconess Medical Center, says one or two of the hospital's 21 patients faced a "high probability of mortality."
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.
The explosions have killed two people and injured at least 23 others.
The Commissioner also urges people to stay indoors, not congregate in large groups.
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.
Gov. Tomblin released the following statement:
"Our thoughts and prayers are with those affected by today's tragic events in Boston. We are monitoring information through the West Virginia Intelligence Fusion Center. No specific threats to West Virginia have been identified at this time."
W.Va. Attorney General released the following statement:
"My heart is heavy today as I read reports coming out of Boston. I am praying for the victims as well as the families of people who were killed or injured in this cowardly attack. The Boston Marathon is a signature and historic event intended to celebrate Patriots Day, and on this day, all Americans need to come together to fight any type of insane attack that targets innocent people.”
About two hours after the winners finished the race there were two explosions near the finish line Monday, killing at least two people and injuring as many as 23 others.
Boston Police and federal authorities are trying to determine what happened.
The White House says President Barack Obama has called Boston's mayor and the Massachusetts governor to express his concern for those injured in the Boston Marathon explosions.
Obama is quoted as telling Mayor Tom Menino and Gov. Deval Patrick that his administration would provide whatever support was needed in responding to the incident.
The president was briefed on the explosions by Homeland Security adviser Lisa Monaco shortly after 3 p.m.
Shortly after the explosions, Secret Service shut down Pennsylvania Avenue outside the White House, cordoning off the area with yellow police tape. Several Secret Service patrol cars also blocked off the entry points to the road.
The White House was not on lockdown and tourists and other onlookers were still able to be in the park across the street from the executive mansion.
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.
The blasts shattered the end of the race Monday, sending authorities out on the course to carry away the injured while stragglers in the 26.2-mile race were rerouted away from the smoking site.
A senior U.S. intelligence official says two more explosive devices have been found and the new devices were being dismantled.
It was not immediately clear what kind of devices had been found. 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.
One runner says he saw at least two dozen people with very serious injuries at the finish line. The runner, a Rhode Island state trooper, says the injuries included missing limbs.
The explosions happened about three hours after the winners had completed the race.
Competitors and race volunteers were crying as they fled the chaos and as bloody spectators were 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. Those who hadn't yet finished the race were rerouted away from the area.
Smoke rose from the blasts, fluttering through the flags lining the route. TV helicopter footage showed blood staining the pavement in the popular shopping and tourist area known as the Back Bay.
Police in Los Angeles, New York City, London and other cities worldwide are stepping up security following explosions at the Boston Marathon.
Los Angeles County Sheriff's spokesman Steve Whitmore says the department has opened an emergency operations center, increased patrols for transit and other critical areas including the Los Angeles Dodgers game Monday night
Chief NYPD spokesman Paul Browne said Monday that critical response teams are deployed around the city. Officials are stepping up security at hotels and other prominent locations.
British police also say they are reviewing security plans for Sunday's London Marathon. It's the next major international marathon. A London Metropolitan Police spokesman says police are working with marathon officials to review security plans.
One woman says she was waiting for her husband to cross the finish line, and, in her words, "it just blew." She described it as "a loud boom, and then glass everywhere." Cherie Falgoust says something hit her head, and she "just ducked."
A runner, Laura McLean of Toronto, says she heard two explosions outside the medical tent. She says, "There are people who are really, really bloody." McLean says, "they were pulling them into the medical tent."
The explosions took place about three hours after the winners crossed the finish line. The second one could be heard a few seconds after the first one.
A runner said, "There are a lot of people down."
Marathon workers were seen carrying one woman, who did not appear to be a runner, to the medical area as blood gushed from her leg.
The White House says President Barack Obama has been notified about the explosions and says the administration is in contact with state and local authorities.
The President has directed the administration to provide whatever assistance is necessary in the investigation and response.
Vice President Joe Biden was on a conference call with gun control activists when staffers turned on televisions in his office Monday to view coverage of the explosions. Biden said during the call that his prayers were with those who suffered injuries.
Bloody spectators were being carried Monday to the medical tent that had been set up to care for fatigued runners. Police wove through competitors as they ran back toward the course.
"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.
A Boston police officer was wheeled from the course with a leg injury that was bleeding.
About three 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.