Many of the more than 170 people injured in the bombings near the Boston Marathon finish line, suffered serious wounds to their legs.
That's because the improvised explosive devices (IEDs) sent shrapnel hurling at a low level across the sidewalks.
Boston hospitals report they have had to perform at least 14 amputations so far.
Losing a limb is an emotionally and physically devastating experience. One day you're whole, the next day - you're not.
And people who lose their limbs - especially in traumatic situations - face a long road to recovery.
Tom Davis has traveled that road.
Davis was staff sergeant in the U.S. Army serving in Iraq in 2006 when a roadside IED blew up the truck he was riding in.
He lost his left leg above the knee, broke both arms, fractured his right knee and a vertebra in his back, cracked bones on his head and suffered traumatic brain injury and post-traumatic stress disorder (PTSD).
But on Monday, Tom Davis won the men's handcycle race in the Boston Marathon, in a time of one hour, seventeen minutes and fifty-nine seconds - five minutes faster than his closest competitor.
We ask him what advice he has for victims of the bombing who have lost limbs.
TED Talk: Aimee Mullins: It's not fair having 12 pairs of legs (1999)
- Tom Davis, handcycle racer from northeast Indiana who lost a leg while serving in Iraq.
- Marilyn Wedler, therapy manager at Turnstone therapeutic center in Fort, Wayne, Indiana.
This segment aired on April 18, 2013.