Exclusive: Boston Marathon bombing report with links to emergency communications recordings.
CONNECT AMARILL0 — Two bombs exploded in the packed streets near the finish line of the Boston Marathon on Monday, killing two people and injuring more than 80 in a terrifying scene of shattered glass, billowing smoke, bloodstained pavement and severed limbs, authorities said.
A senior U.S. intelligence official said two other explosive devices were found near the end of the 26.2-mile course.
At the White House, President Barack Obama vowed that those responsible will "feel the full weight of justice."
There was no word on the motive or who may have launched the attack, and police said no suspect was in custody. Authorities in Washington said there was no immediate claim of responsibility.
"They just started bringing people in with no limbs," said runner Tim Davey, of Richmond, Va. He said he and his wife, Lisa, tried to keep their children's eyes shielded from the gruesome scene inside a medical tent that had been set up to care for fatigued runners, but "they saw a lot."
"They just kept filling up with more and more casualties," Lisa Davey said. "Most everybody was conscious. They were very dazed."
The twin blasts at the race took place almost simultaneously and about 100 yards apart, tearing limbs off numerous people, knocking spectators and at least one runner off their feet, shattering windows and sending smoke rising over the street.
Some 23,000 runners took part in the race, one of the world's oldest and most prestigious marathons. One of Boston's biggest annual events, the race winds up near Copley Square, not far from the landmark Prudential Center and the Boston Public Library. It is held on Patriots Day, which commemorates the first battles of the American Revolution, at Concord and Lexington in 1775.
Boston Police Commissioner Edward Davis asked people to stay indoors or go back to their hotel rooms and avoid crowds as bomb squads methodically checked parcels and bags left along the race route. He said investigators didn't know whether the bombs were planted in mailboxes or trash cans.
He said authorities had received "no specific intelligence that anything was going to happen" at the race.
The Federal Aviation Administration barred low-flying aircraft from within 3.5 miles of the site.
Obama was briefed on the explosions by Homeland Security adviser Lisa Monaco. Obama also told Mayor Tom Menino and Gov. Deval Patrick that his administration would provide whatever support was needed, the White House said.
"We still don't know who did this or why," Obama said, adding, "Make no mistake: We will get to the bottom of this."
A few miles away from the finish line and around the same time, a fire broke out at the John F. Kennedy Library. The police commissioner said it may have been caused by an incendiary device but didn't appear to be related to the bombings.
"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.
About four hours into the race and two hours after the men's winner 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.
By that point, more than 17,000 of the runners had finished the race, but thousands of others were farther back along the course.
The Boston Police Department said two people were killed. Hospitals reported at least 82 injured, at least eight of them critically.
A senior U.S. intelligence official said the two other explosive devices found nearby were being dismantled. The official spoke on condition of anonymity because he was not authorized to discuss the findings publicly.
EXCLUSIVE: LISTEN TO RECORDED BOSTON PD EMERGENCY AUDIO COMMUNICATIONS HERE: