BOSTON - The bombs that blew up seconds apart at the finish line of one of the world's most storied races left the streets spattered with blood and glass, three dead, including an 8-year-old boy, more than 140 wounded and gaping questions of who chose to attack at the Boston Marathon and why.
Federal investigators said no one had claimed responsibility for the bombings one of the city's most famous civic holidays, Patriots Day. But the blasts among the throngs of spectators raised fears of a terrorist attack.
President Barack Obama was careful not to use the words "terror" or "terrorism" as he spoke at the White House Monday after the deadly bombings, but an administration official said the bombings were being treated as an act of terrorism.
"We will find out who did this. We'll find out why they did this," the president said. "Any responsible individuals, any responsible groups, will feel the full weight of justice."
The Pakistani Taliban, which has threatened attacks in the United States because of its support for the Pakistani government, on Tuesday denied any role in the marathon bombings.
The group's spokesman, Ahsanullah Ahsan, denied involvement in a telephone call with The Associated Press. He spoke from an undisclosed location.
The FBI took charge of the investigation into the bombings, serving a warrant late Monday on a home in suburban Boston and appealing for any video, audio and still images taken by marathon spectators.
The fiery explosions took place about 10 seconds and about 100 yards apart, knocking spectators and at least one runner off their feet, shattering windows and sending dense plumes of smoke rising over the street and through the fluttering national flags lining the route.
As many as two unexploded bombs were found near the end of the 26.2-mile course as part of what appeared to be a well-coordinated attack, but they were safely disarmed, according to a senior U.S. intelligence official, who also spoke on condition of anonymity because of the continuing investigation.
WBZ-TV reported late Monday that law enforcement officers were searching an apartment in the Boston suburb of Revere.
Massachusetts State Police confirmed that a search warrant related to the investigation into the explosions was served Monday night in Revere, but provided no further details.
Some investigators were seen leaving the Revere house early Tuesday carrying brown paper bags, plastic trash bags and a duffel bag.
Police said three people were killed. An 8-year-old boy was among the dead, according to a person who talked to a friend of the family and spoke on condition of anonymity. The person said the boy's mother and sister were also injured as they waited for his father to finish the race.
Hospitals reported at least 144 people injured, at least 17 of them critically. At least eight children were being treated at hospitals.
Brookhaven couple describe explosion
One runner from Brookhaven told Channel 2's Kerry Kavanaugh he crossed the finish line about 20 minutes before he heard the explosion. His wife pulled out her cellphone and recorded some of the chaos that followed.
"The best of the best run this marathon. It's a qualifier. It's a goal of mine, been on the bucket list for a long time," Brett Alison told Kavanaugh.
Alison said he crossed the finish of the Boston Marathon for the second time Monday afternoon.
He received the traditional jacket and medal, gifts that would soon take on a whole new meaning.
"I was praying it wasn't what I thought it was," Alison said.
"When it first happened, we kind of sit there and look at each other, 'Is it really what we think that it was?'" Leslie Alison said.
"It just sounded different. I never heard anything like that before. Two seconds later another one went off," Brett Alison said.
Thirteen seconds separated the two blasts at the finish line on Boston's Boylston Street.
Luckily the Alisons were already back at their apartment around the corner from the finish line.
Police immediately began evacuating the area.
"When you hear policemen yell, 'Run,' it put us in a little bit of a panic," Brett Alison said.
Leslie Alison shot video with her cellphone that showed hordes of people running away from the finish line of the marathon while the first responders raced into the scene.
Brett Alison told Kavanaugh everything that happened was still sinking in.
"It's surreal with it happening on Patriots Day and it means a lot for the city itself and the country," he said.
Brett Alison told Kavanaugh he already knew where he would be on Patriot's Day next year.
"I think that's what they want to do is set fear in our hearts and not have us come back to a race like this...but it makes do it even more," He said.
Marathon runners return to Atlanta
Marathon runners from metro Atlanta continued to return home from Boston Tuesday.
Channel 2's Amy Napier Viteri talked to runners who were on the last flight out of Boston Monday night, including the chairman of the Atlanta Track Club.
Several runners just made it onto their flights before travel was shut down out of Boston. Viteri watched as family members carrying signs gave loved ones big hugs after seeing them walk into the arrival area.
Both families Viteri talked with said they learned early on their loved ones were safe.
Charlie Crawford with the Atlanta Track Club was one of those people who returned Monday night. He told Viteri many of the runners on the flight didn't know the extent of the injuries and tragedy in Boston until they got on the plane and had a chance to read and watch some of the coverage.
"Before I boarded the flight I didn't know there were fatalities. I understand an 8-year-old son an eight year old boy was killed," Crawford said. "It's great to be back in Atlanta. It was a horrific end to the day in Boston. My heart… it's a tough day."
"Just a lot of emotion because it's a pretty grueling, amazing race. And then for the day to end like this it's hard to even rehash what to say," runner Michelle Frank told Viteri. "You want to rehash the race but like the pain I'm feeling right now doesn't matter because there's people not alive and there's people who lost their legs."
Crawford said Atlanta Mayor Kasim Reed was also on board that flight from Boston. Crawford told Viteri there are always strong security measures in place for the Peachtree Road Race in Atlanta but they will be talking with city leaders about elevating security for this year's race.