Boston Marathon Bombing: Networks Report Three Dead, 144-Plus Injured (Video)

Boston Marathon Explosion Scene Screengrab - H 2013

Boston Marathon Explosion Scene Screengrab - H 2013

UPDATED: Two explosions rocked the finish line of the annual race in Boston, with at least a dozen people reportedly injured.

Two bombs were detonated at the finish line of the Boston Marathon on Monday, at approximately 2:45 pm ET, hours after the first runners had completed the race.

Both cable and broadcast networks broke into afternoon programming to cover the attack, which, according to one reporter, had injured at least a dozen people. An eyewitness told the site that there was "blood everywhere" at the scene. By Monday evening, it was reported that three people were dead, including an 8-year-old child, and more than 144 were injured.

Two more explosive devices were found by authorities, who were handling them in a controlled manner. A third explosion, at JFK Library, occurred, but appears to be unrelated.

CNN, NBC, CBS, Fox News, Fox, MSNBC, CNBC and ABC mixed coverage from affiliate stations and aerial shots in Boston to cover the mayhem. The explosion occurred north of Boylston street, near a cherry picker right before the finish line.

A suspect is reportedly being guarded at a hospital. CBS quotes a law enforcement agent saying that police have surveillance tape of a man carrying multiple backpacks into the explosion area about 20 minutes before the detonations. [UPDATE, 6:50 p.m.: CBS News reports that a Saudi national is in custody, but the individual denies involvement in the bombing.]

[UPDATE, 8:00 p.m.: The Boston Globe reports that authorities are questioning a person of interest at Brigham and Women's Hospital, two miles from the bomb location.]

There are conflicting reports as to fatalities; Fox News has reported three lives lost, while the Post has relayed 12 dead. Smoke continues to rise from the scene. Victims were initially brought to a medical tent meant for runners, and some have since been brought to Massachusetts General hospital; one report had 10 people with amputated limbs at that hospital. [UPDATE, 7:01 p.m.: CNN reports two people are confirmed dead, including an 8-year-old child, and that more than 110 people were wounded.]

[UPDATE, 8:03 p.m.: The number of injured has reached 132.]

[UPDATE, 8:59 p.m.: Boston police commissioner says number of fatalities is three, while the number of wounded is up to 141.]

Brian Williams is hosting a special report on the situation for NBC, while CBS' anchor Scott Pelley is leading his network's coverage. George Stephanopoulos and Diane Sawyer are at the helm for ABC News. A special one-hour edition network's World News Tonight will be dedicated to covering the situation, as will Nightline. Stephanopolous will be in Boston on Tuesday morning for Good Morning America.

CNN has sent Anderson Cooper and Chris Cuomo to Boston for their coverage. Poppy Harlow, Brian Todd, Jason Carroll, Pete Hamby, Zain Asher and Maria Santana will also be on the scene later Monday. Additional contributors for CNN will also include Fran Townsend, Peter Bergen, Tom Fuentes and Mike Brooks.

On Fox News, Shepard Smith led the coverage in the 3 p.m. ET hour, and will continue to anchor the network's reporting on the explosions through the evening; Fox's The Five is being pre-empted for continuing coverage.

Fox News plans to air On the Record With Van Susteren live from Boston for a two-hour show beginning at 10 p.m. ET. Additionally, Smith will go live at midnight ET for a one-hour program. Tuesday morning's Fox & Friends First will be pre-empted at 5 a.m. ET for an additional hour of Fox & Friends co-hosted by Steve Doocy, Brian Kilmeade and Megyn Kelly.

Tragically, families from Newtown, Conn. -- the site of the mass school shooting last December -- were seated in the VIP section near the explosions.

Video of the explosion is below:

Philiana Ng contributed to this report.