Dozens of patients have been released from hospitals around the Boston area.
At Massachusetts General Hospital, all four amputations performed there were above the knee, with no hope of saving more of the legs, said Dr. George Velmahos, chief of trauma surgery.
"It wasn't a hard decision to make," he said Tuesday. "We just completed the ugly job that the bomb did."
The bombs exploded 10 or more seconds apart, tearing off victims' limbs and spattering streets with blood. The blasts near the finish line instantly turned the festive race into a hellish scene of confusion, horror and heroics.
The blasts killed 8-year-old Martin Richard, of Boston, and 29-year-old Krystle Campbell, of Medford. The Shenyang Evening News, a state-run Chinese newspaper, identified the third victim as Lu Lingzi. She was a graduate student at Boston University.