UPDATE: Deadly explosions at the Boston Marathon

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Boston Marathon explosion (PHOTO: CBS News)

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(CNN) — Two bombs struck near the finish line of the Boston Marathon on Monday, turning a celebration into a bloody scene of destruction.

The blasts threw people to the ground, killing two and injuring dozens. One of the dead was an 8-year-old boy, according to a state law enforcement source.

Hospitals reported at least 134 people being treated, at least 17 of them in critical condition and 25 in serious condition. At least eight of the patients are children.

At least 10 people injured had limbs amputated, according to a terrorism expert briefed on the investigation.

Doctors are “pulling ball-bearings out of people in the emergency room,” the expert said, suggesting the bombs were designed to propel shrapnel.

“Any responsible individuals, any responsible groups, will feel the full weight of justice,” President Barack Obama vowed.

Boston “is a tough and resilient town,” he said, adding that Americans will stand by Bostonians “every single step of the way.”

‘Like a huge cannon’

The terrorist attack, near the marathon’s finish line, triggered widespread screaming and chaos, shattered windows and barricades and sent smoke billowing into the air at Copley Square.

The blasts were about 50 to 100 yards apart, officials said, on a stretch of the marathon course lined with spectators cheering runners through the final yards of a 26-mile, 385-yard endurance feat.

“It felt like a huge cannon,” a witness told CNN about one of the blasts.

Photos from the scene showed people being carried away on stretchers. One man in a wheelchair had blood all over his face and legs.

The bombs shook buildings, sending people to seek shelter under tables, witnesses said.

Federal authorities are classifying the bombings as a terrorist attack, but it’s not clear whether the origin was domestic or foreign, a federal law enforcement official with knowledge of the investigation said.

A federal law enforcement official told CNN that both bombs were small, and initial tests showed no C-4 or other high-grade explosive material, suggesting that the packages used in the attack were crude explosive devices.

Another explosive device found

Authorities in Boston found at least one other explosive device that they were dismantling, Boston Police Commissioner Ed Davis said.

Rep. Bill Keating of Massachusetts, meanwhile, said there were two more found.

One unexploded device was found at a hotel on Boylston Street near the bomb site and another unexploded device was found at an undisclosed location, Keating, a Democrat and member of the House Homeland Security committee, said, calling the bombing a “sophisticated, coordinated, planned attack.”

Davis said a third blast at the John F. Kennedy Presidential Library was believed to be related to the marathon bombings, but police later said that incident was believed to be fire-related. The library said all staff and visitors are safe.

It was unclear who may have planted the marathon bombs. There were no credible threats before the race, a state government official said.

There is no suspect in custody, but many people are being questioned, Davis said.

As authorities searched the scene, numerous suspicious packages were found, possibly because people fled the area, leaving items behind. Investigators were checking them.

All off-duty Boston police were called in.

The Marriott hotel at Copley Place was evacuated as a precaution.

The Lenox Hotel was also evacuated as a precaution, the Boston Globe reported.

‘Horrific day’

Crowds were in the area watching the runners take part in the world’s oldest annual marathon.

It was also Patriot’s Day, commemorating the opening battle of the Revolutionary War.

Within seconds, the festive occasion turned into devastation.

“This is a horrific day in Boston,” Massachusetts Gov. Deval Patrick said in a statement.

“My thoughts and prayers are with those who have been injured. I have been in touch with the president, Mayor (Thomas) Menino and our public safety leaders. Our focus is on making sure that the area around Copley Square is safe and secured. I am asking everyone to stay away from Copley Square and let the first responders do their jobs.”

U.S. Attorney General Eric Holder spoke with FBI Director Robert Mueller and U.S. Attorney Carmen Ortiz, a Justice Department official said.

Holder has directed the full resources of the Justice Department to be deployed to ensure the matter is fully investigated, the official said.

The Federal Aviation Administration placed a flight restriction over the site of the blasts.

Other cities, including New York and Washington, tightened security as a result. Following standard protocol, the White House cleared out an area in front of the West Wing.

“If you see something, say something,” Mark Boughton, mayor of Danbury, Connecticut, wrote on Twitter. “All cities will be on a heightened state of alertness per Homeland Security protocols.”

Mike Baingon, who works at the Atlantic Fish Company in Boston, said an explosion took place in front of the restaurant and that he was right by the front door at the time.

The explosions occurred at about 2:45 p.m., more than two hours after the first of the race’s nearly 27,000 runners had crossed the finish line, CNN Producer Matt Frucci reported.

The race was halted as was subway service into the area.

Runners east of Massachusetts Avenue were directed to Boston Common; those west of Massachusetts Avenue were directed to Kenmore Square, the state’s emergency management agency said.

Troops from the Massachusetts National Guard, already at the site as part of the marathon’s security and crowd-management plan, were assisting police as well.

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Alix Bryan April 15, 201310:44 pm

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Alix Bryan April 15, 20138:38 pm

Hospitals have treated 141 people after the Boston Marathon bombings, officials at those facilities said Monday night. Two people died in the terror attack, including an 8-year-old boy, a state law enforcement source said.

Alix Bryan April 15, 20137:55 pm

The bombs that went off at the Boston Marathon on Monday resulted in at least 10 lost limbs and left doctors picking ball bearings out of victims in the emergency room, a terrorism expert briefed on the investigation said.

Alix Bryan April 15, 20137:35 pm

CBS 6 spoke with the Richmond Red Cross and they said they are not soliciting either blood or money, nor or any national chapters. We will update if this changes.

Alix Bryan April 15, 20137:25 pm

Alix Bryan April 15, 20136:41 pm

Youngest injury we know of at this time, based on CBS reporting, is 3-yr. old child.

Alix Bryan April 15, 20136:13 pm

Injury count growing. Hospitals say they are treating at least 80 wounded after Monday’s bombings at the Boston Marathon. Two people have been killed, according to Boston police.

Alix Bryan April 15, 20136:08 pm

Alix Bryan April 15, 20136:03 pm

Suspects being questioned–no one is in custody, per CBS. There have been no credible claims of responsibility. Do not know if this is foreign or domestic at this time.

Alix Bryan April 15, 20135:41 pm

Hospitals say they are now treating 69 people who were wounded in Monday’s bombings at the Boston Marathon.

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Scott Wise April 15, 20134:48 pm

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Scott Wise April 15, 20134:42 pm

CNN: Investigators are working to dismantle other explosive devices found after the Monday bombings at the Boston Marathon that killed two people and wounded about two dozen, a federal law enforcement source said.

Scott Wise April 15, 20134:39 pm

Scott Wise April 15, 20134:34 pm

Virginia Governor Bob McDonnell released the following statement on today’s explosions at the Boston Marathon:

“Our thoughts and prayers are with the people of Boston as they go through this tragic situation. As a longstanding matter of policy, this office does not comment on security measures and precautions taken by state authorities and agencies. We are closely monitoring this ongoing event in conjunction with State Police and law enforcement partners at the local and federal levels.”

Scott Wise April 15, 20134:15 pm

Scott Wise April 15, 20134:14 pm

The following is list of Boston Marathon runners who’ve listed Richmond, Virginia as their hometown: http://on.wtvr.com/0KKxfKX

Alix Bryan April 15, 20134:14 pm

Today’s race was in tribute to victims of Newtown.
Boston Athletic Association president Joanne Flaminio told ESPN that here was “special significance” to the fact that the race is 26.2 miles long and 26 people died at Sandy Hook Elementary school.

Alix Bryan April 15, 20134:11 pm

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This picture was posted on Twitter by user @theoriginalwak

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Scott Wise April 15, 20133:46 pm