(CNN) -- Investigators are pleading for help in
hunting down whoever triggered a pair of bombings that left a gruesome
scene at the Boston Marathon.
The blasts, which killed
an 8-year-old boy and two others, marked a grotesque end to what should
have been a celebration of triumph.
One man's legs were instantly blown off, yet he kept trying to stand up.
Exhausted marathoners had to muscle the energy to flee the bloody scene.
And more than 140 people were hospitalized, some in critical condition.
"No piece of information or detail is too small," the
FBI Boston Division said, asking the public for any information or images that might provide clues.
While authorities search
for answers, many are at a loss to explain why anyone would target the
annual event that celebrates thousands of runners from around the world.
A stunning attack
Both blasts happened in
quick succession, near the row of international flags that led up to the
finish line. The impact was so powerful, it whipped the limp flags
straight out, as if they were caught in a hurricane.
It also knocked 78-year-old runner Bill Iffrig to the ground.
"I was just approaching
the last straightaway to the finish line, and I had a good day and was
feeling really good, and I got down to within about 15 feet of the
finishing apron and just tremendous explosion, sounded like a bomb went
off right next to me," Iffrig said.
"The shock waves just hit my whole body and my legs just started jittering around. I knew I was going down," he said.
Iffrig was not seriously injured. But trails of blood, severed arms and legs and other body parts littered the scene nearby.
At least 144 people were
hospitalized, with at least 17 in critical condition and 25 in serious
condition, officials said. At least eight of the patients are children.
Dr. Albert Pendleton, an
orthopedic surgeon who was helping staff the race's medical tent, told
CNN on Tuesday it was "basically like the bomb took out he legs of
everybody."
"It was horrific," he said.
A terrorism expert
briefed on the investigation said doctors had removed ball bearings from
patients wounded in the bombings, suggesting the bombs were designed to
propel shrapnel.
But Dr. Ron Walls of
Brigham and Women's Hospital, which received 31 patients, said the
debris found in some patients' wounds did not appear to be from ball
bearings.
"Everything we saw was
sort of ordinary ambient material that could have been propelled by the
blast but was not added to the device," Walls said. "It was not the kind
of things that would be added to a device to make it more injurious
than it otherwise would be."
At Massachusetts General
Hospital, several patients suffered from injuries to lower limbs that
will require "serial operations" in the coming days, trauma surgeon
Peter Fagenholz said Monday night.
He said the most serious wounds "have been combined, complex lower injuries that involve blood vessels, bone and tissue."
Numerous patients had to have limbs amputated, Fagenholz said.
The hunt for clues
Investigators don't know
who was behind the attack, or whether it was spawned domestically or
from afar. But federal authorities are classifying it as an act of
terrorism.
Federal and local
investigators -- including bomb technicians -- searched an apartment in
nearby Revere, the city's fire department
posted on Facebook
early Tuesday. The search took place by consent, according to a federal
law enforcement source, meaning no search warrant was needed.
But authorities have not officially linked the search to the marathon bombings.
A federal law
enforcement official said both bombs were small, and initial tests
showed no C-4 or other high-grade explosive, suggesting that the
packages used in the attack were crude.
President Barack Obama,
who said Monday the bomber or bombers would "feel the full weight of
justice," received overnight briefings on the investigation, a White
House official said.
The explosions went off
near the finish line about 4 hours and 9 minutes into the race, within a
10-minute window of the average finish time for the marathon.
But the fact that the
blasts took place near the end of the race "seems to indicate this was
not geared toward maximum damage," said a former federal law enforcement
official who now works in the intelligence community.
"It may speak volumes
about the (level of) planning that went into this," the source said. "It
raises questions ... why didn't the bombs go off when the crowd was
packed in like sardines when the winners were crossing the finish line?
It could mean the people behind it couldn't get access to the area when
they originally intended."
Officials have no suspect in custody, but many people are being questioned, Boston Police Commissioner Ed Davis said.
Investigators warned
police to be on the lookout for a "darker-skinned or black male" with a
possible foreign accent in connection with the attack, according to a
law enforcement advisory obtained by CNN. The man was seen with a black
backpack and sweatshirt and was trying to get into a restricted area
about five minutes before the first explosion, the lookout notice
states.
Davis said authorities found at least one other explosive device that they were dismantling.
But Rep. Bill Keating, D-Massachusetts, said two undetonated devices were found.
One was discovered at a
hotel on Boylston Street near the bomb site, and another was found at an
undisclosed location, said Keating, a member of the House Homeland
Security Committee. He called the bombing a "sophisticated, coordinated,
planned attack."
Any unexploded devices
could provide a treasure trove of information such as fingerprints and
indications of the bomb maker's design, said the former federal law
enforcement official.
Late Monday night,
authorities said they were still getting reports about suspicious
packages, but some may be abandoned belongings left by fleeing
spectators.
Davis said that while no new devices had been found, he is "not prepared to say we're at ease at this point in time."
'Just like going back' to Iraq
Nurses Stephen Segatore
and Jim Asaiante were stationed near the finish line, expecting to treat
the usual ailments from runners -- cramps and dehydration.
Suddenly, they found themselves in a battlefield, with blood and debris everywhere.
"For me, it was just like going back to being in Iraq in 2006-2007," said Asaiante, an Army captain who served an 18-month tour.
"I heard the first IED,
and I know there's never one. The bad guys always set up two or three"
improvised explosive devices, he said.
The plumes of smoke and
images of bloodied victims running down streets also triggered haunting
memories of the terrorist attacks of 9/11.
Tami Hughes had just crossed the finish line and was looking for her husband when she heard a deafening explosion.
"I didn't know if it was
a small aircraft going into the building," said Hughes, who was in the
bustling financial district during the 9/11 attacks.
"I turned around and
immediately saw the whitish-brownish smoke billowing up four or five
stories and I couldn't believe that, you know, could it be a bomb? And I
stared at it and about five or seven seconds later, when the second one
went off, I knew immediately that it was something coordinated or
organized."
Never the same again
The Boston Marathon is the world's oldest annual marathon, dating back to 1897.
It's a tradition that
not only symbolizes the arrival of spring in Boston, and it also marks
Patriots Day, which commemorates the day of the opening battle of the
Revolutionary War.
Each year, more than 20,000 pound the pavement through the winding streets of Boston as thousands of spectators cheer them on.
After Monday's tragedy, some wondered whether the spectacle would ever happen again.
"The Boston Marathon has
endured two world wars and many other things," said Fred Treseler, who
has helped train more than 3,000 athletes for the race.
"I am quite sure there will be a Boston Marathon next year. But for certain, the Boston Marathon has been changed forever."
CNN staff in Boston, New York, Atlanta and Washington contributed to this report.