Morning of the Marathon (04:01)

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See news coverage of the start of the 117th Boston Marathon. Hear from people who were there that day including the Corcoran and the Norden families. (Credits)

Explosion Footage (02:42)

Celeste, Sydney, and Kevin Corcoran, JP Norden, Patrick Downes, and Jessica Kensky recall where they were before the first bomb exploded.

Immediately After Explosions (02:27)

JP Norden recalls the moments after the attack. He lost a foot and his brother Paul lost his leg. EMT Jim Allen remembers the scene as bystanders helped assist victims.

Injuries at Boston Marathon (03:21)

Jessica Kensky recalls seeing Patrick Downes' detached foot. Tyler Corcoran received news that his mom was in critical condition.

Peak of Fear (02:19)

Tyler Corcoran remembers waiting on news of his mom and sister Sydney who nearly died. Patrick Downes recalls waking up in the hospital.

Large Crime Scene (04:48)

Boston Police asked for the public's help finding evidence. Liz Norden's sons were in different hospitals being treated for injuries.

Newlyweds With Complex Injuries (02:38)

Kensky and Downes were in different hospital for five weeks following the bombing. The husband and wife tell the story of how they met.

Mother and Daughter Recover Together (03:54)

Celeste Corcoran lost both of her legs. Sydney almost died on the sidewalk. "The Boston Globe" photographer John Tlumacki took widely published photographs.

Video Evidence of Suspects (03:14)

Three people were killed and more than 100 injured at the Boston Marathon. Authorities received a huge amount of information from the public.

City United (02:40)

President Obama arrived in Boston and made a speech in support of the city after the terrorist attack.

Psychological Suffering (04:07)

Kensky was in constant pain with her deformed leg after many limb salvage surgeries. She and her husband Patrick Downes began to feel happy again after getting a service dog.

Leaving Someone Behind (02:53)

Paul Norden went home to his mom's house while JP was still recovering in the hospital. Sydney Corcoran struggled to deal with her own injury and her mother's.

Walking Without Legs (02:29)

Celeste Corcoran talks about her first prosthetic legs. Her family recalls her crying every day until she met with a prosthetist in Florida.

Suspect Photos Released (03:28)

Five hours after the FBI released their photos, the suspects killed a police officer on the MIT campus before committing a carjacking. Hear the 911 call.

Shots Fired (02:16)

The Boston Marathon bombing suspects opened fire after being surrounded in Watertown. The younger brother escaped and the older brother died.

Manhunt and Lockdown (02:00)

Boston residents were instructed to stay indoors. Police learned the identities of the Tsarnaev brothers by taking fingerprints from Tamerlan Tsarnaev's dead body.

Helicopter Footage (03:19)

After the lockdown was lifted, police received a call from David Henneberry. Hear the 911 report of a man covered in blood in a boat. The suspect was taken into custody with multiple gunshot wounds.

Chronic Pain One Year Later (02:07)

Kensky and Downes threw a party one year after the bombing. She pretended to feel better, but her leg was in constant pain.

Walter Reed Medical Center (02:53)

Kensky was in constant pain, but was fearful of losing her second leg. She kept a pain journal to help determine whether she should have her second leg amputated.

Corcoran Family Post Traumatic Stress (04:13)

After the bombing, Sydney Corcoran felt out of control and her eating disorder intensified. Tlumacki brings the family a book of photographs. Tyler talks about his father's struggle with alcohol.

Intense PT (02:18)

Kensky talk about physical therapy at Walter Reed. Downes feels honored to be accepted at the military hospital.

Adapting to Life After Bombing (03:55)

JP Norden struggled to work as a laborer after having his leg amputated and decided to start his own business. EMT Jim Allen was his first customer.

FBI was Warned About Suspects (02:33)

Tamerlan and Dzhokhar Tsarnaev moved to the U.S. from Dagestan, Russia. Authorities tried to understand what led to the brothers becoming terrorists.

Media Coverage of Bombers (03:16)

"Inspire" magazine targeted young, English speaking Muslim men living in America. Journalists were threatened for covering the suspects.

Running Out of Hope (03:32)

Kensky's parents talk about their struggle. She is not healing properly and the care team at Walter Reed cannot figure out how to treat her.

Identity Crisis (02:13)

Kensky and Downes both use wheelchairs to get ready for the day. They still struggle to adapt to their new reality.

Beach Legs (03:45)

Celeste Corcoran talks about missing her legs. A special prosthetic allows her to swim and walk on the sand.

Death Penalty Case (02:51)

Tsarnaev was tried in federal court for the bombing that killed four and injured hundreds. Survivors talk about their experiences as witnesses.

Boston Marathon Bombing Victims (04:25)

Liz Norden went to every day of Tsarnaev's trial. The defense tried to establish that his big brother made him do it. The families of those killed testified in court.

Unrepentant Killer (02:20)

Prison camera footage shows Tsarnaev looking into the camera. The victim's families argued against the death penalty in court.

Boston Marathon Bombing Verdict (02:27)

Survivors learn that Tsarnaev was sentenced to death. The Corcoran family and Liz Norden felt a sense of justice.

Three Years Later (03:03)

Kensky and Downes drive to Boston where he will be participating in the marathon.

Reclaiming the Finish Line (05:55)

Downes runs the Boston Marathon. Norden's wife also runs. Kensky and Corcoran watch from the sidelines.

Credits: Marathon: The Patriots' Day Bombing (107:13)

Credits: Marathon: The Patriots' Day Bombing