In this image from video provided by WBZ TV, spectators and runners run from what was described as twin explosions that shook the finish line of the Boston Marathon, Monday, April 15, 2013, in Boston.
Boston -- Boston Police say two people are dead after twin explosions at the Boston Marathon's finish line, and at least 73 people are injured.
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.
See Also: How to find a marathon runner
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.
VIDEO: 10 News reporter Noah Pransky live from the scene
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.
617-635-4500 - Mayor's hotline for info about people
800-494-TIPS - Info about the incidents
Boston Police: No one in custody
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.
Witnesses describe explosions
Spectators and runners are describing the twin explosions that shook the finish line of the Boston Marathon on Monday.
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.
Official: Cell phone service shut down in Boston
A law enforcement official says cellphone service has been shut down in the Boston area to prevent any potential remote detonations of explosives.
Officials say if you're trying to contact someone who may have been at the race, to call 617-635-4500, an information hotline.
No-fly zones ordered over explosion sites
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.
Obama notified of explosions
The White House says President Barack Obama has been notified about the explosions at the finish line of the Boston Marathon.
The White House says the administration is in contact with state and local authorities and directed his administration to provide whatever assistance is necessary in the investigation and response.
See Also: Obama - "We will find out who did this"
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.
Secret Service spokesman Ed Donovan says it has expanded its security perimeter at the White House, and that the measure was taken "out of an abundance of caution." He says it is not unusual to expand or contract the security perimeters.
Shortly after the explosions Monday, 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.
Security beefed up worldwide after Boston blasts
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.
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