The bombmakers behind the Boston Marathon explosions weren't looking to scare people, a trauma surgeon with nine years of military experience told ABCNews.com.
They intended to kill, said former Navy surgeon Dr. Gary Schwendig.
"That person or those people did everything they could to create a bomb that damaged and injured as many people as they possibly could," said Schwendig, who now works at Scripps Health in San Diego.
Schwendig said a bomb's shock wave alone was often enough to rupture blood vessels in victims' lungs and other organs in a way that proves fatal, and that debris picked up by explosions – fences, barricades, wood – tends to fly at people, severing limbs. Shrapnel packed into bombs is made to pepper victims with nails and metal ball bearings, severing veins and arteries.
"It's just one more way to hurt people," Schwendig said of the shrapnel Boston doctors said was built into the bombs. "A nail that is tumbling through the body – that nail is an-inch-and-a-half long and it's tumbling and it's going to cut right through that artery."
Still, most of the ball bearings and other pieces of shrapnel will probably remain with the victims for the rest of their lives, he said. Removing the fragments could cause more damage and increase the likelihood of infection, so trauma doctors often leave the shrapnel where it is.
Many victims of the Boston Marathon bombings face possible amputations in the coming days and months, hospitals reported.
Brigham and Women's Hospital has already performed one amputation, and is working to save another patient's injured limb. Massachusetts General Hospital has amputated four limbs so far, and is treating two patients who could face amputation in the coming days. At Tufts Medical Center, doctors have not yet performed any full amputations, but four victims have limb-threatening injuries.
Dr. Alex Jahangir, an orthopedic trauma surgeon at Vanderbilt University Medical Center in Nashville, Tenn., said blast wounds were rare but cause severe, vast injuries. He said he rarely performs amputations within the first day of an injury because it can take 24 hours to determine the full extent of the damage.
Instead, Jahangir performs an initial surgery simply to clean the wound and remove dead bone and muscle. He may later perform an amputation, depending on whether the limb is getting enough blood flow, whether it has enough healthy tissue and whether there's an infection present.
Sometimes, the patient has a choice between amputation and salvaging a limb, Jahangir said. But many times patients choose amputation because the recovery is faster.
Amputees are usually fitted with prosthetics and sent to rehabilitation to learn how to use them within six to eight weeks, Jahangir said. Patients who don't chose amputation often undergo 15 or 20 surgeries, and they may need to wait six to eight months to make sure the bone is healed before they can start walking.
"That process takes two to three years, and at the end of that, they still may wish that'd have gotten it amputated," Jahangir said. "You'll have the leg, but it won't be the same leg you had."