That's according to the Boston Globe:
The bombing claimed the life of Martin Richard, an eight-year-old boy from Dorchester whose mother and sister were grievously injured. He was the son of Bill Richard, a community leader from Dorchester’s Ashmont neighborhood, officials said.
Television station WHDH said Martin's mother and sister are in the hospital. The mother had surgery for a brain injury the station described as "serious." The sister, who is six years old, lost one of her legs. The family was there to watch Bill Richard finish the race.
Update (3:35 p.m., April 17): Contrary to that WHDH report, the Associated Press later said Bill Richard was not a marathon runner. The family, which included another son, had gone to get ice cream, according to the AP, and returned to an area near the finish line. Bill Richard and the other son were not injured.
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