Photos taken of the Boston Marathon explosion carnage showed horrific images of smeared blood on the sidewalk, blown out windows and bystanders rushing to aid multiple people who had lost limbs and suffered other severe injuries.
But amidst the chaos of what some described as a "war zone," images also emerged on Twitter, Instagram, Facebook and other social media that sent speculation and conspiracy theories flying.
One of the most talked about photos, which was taken by a spectator, captured a mysterious figure walking on top of a building near the finish line, prompting thousands of users to ask about the "man on the roof."
College student Dan Lampariello told ABC News he was taking photos along the race sidelines when he happened to capture the moment one of the bombs exploded.
"I was about 200 feet from the finish line … right in front of the Mandarin Hotel. My aunt was actually running in the marathon. We were out there to cheer her on," Lamperiello said Monday. "We thought maybe it was fireworks at first, but when we saw the second explosion we definitely knew that something was wrong."
But his original picture also showed the unidentified person walking on the roof of a building near the site of the second bomb explosion, which launched a debate on Twitter over whether the mystery person was involved.
A tweet about the photo from @Fraank_Oceaan, a parody account for the musician Frank Ocean, said "Who's that guy on the roof?? #BostonMarathon #PrayforBoston" and has now been re-tweeted almost 3,000 times.
One twitter user, @DougieOliver, said the picture was "the spookiest thing I have ever seen."
The picture of the guy on the roof overlooking the second explosion is the spookiest thing I have ever seen. #BostonMarathon
— Douglas Oliver (@DougieOliver) April 15, 2013
Another twitter user, Heather Swick, called the photo "eerie."
That "Mystery man on the roof" photo is seriously eerie, even if it's just some dude wondering what all the commotion is… #bostonmarathon
— Heather Swick (@heathermeg91) April 16, 2013
But other users aren't so sure. Two Twitter users, Sue Blanton and @jwbul287 both thought the reports that the man was involved were "ridiculous"
"@ jwbul287: The man on the roof above the explosion is ridiculous." People always on the roof in Boston
— Sue Blanton (@Cherokey7) April 16, 2013
At around 3 p.m. Monday, two bombs were set off near the finish line of the Boston Marathon. At least three people are dead and at least 176 people, including 10 children, were injured in the bombing, according to the latest ABC News count. At least 17 people are in critical condition.
The Boston Police told ABC News the "man on the roof" photograph was being sent to the FBI for analysis, like all the other photos from the incident, but was getting no more priority than others and did not raise any undue suspicion.
Boston Police said this morning they still have no suspects in custody and are continuing to interview witnesses. Federal officials said at a press conference they believe there is no longer an "imminent threat" in the area.
FBI special agent in charge Richard DesLauriers said investigators had already received "voluminous" tips and were "logically" following up on leads.
ABC News' Aaron Katersky contributed to this report