Martin died from his injuries. His sister Jane, 7, lost a leg, while their mother Denise had surgery for a brain injury, WHDH reported. A third child, an older son, was reportedly not injured.
In a statement issued Tuesday, Bill Richard said, "My dear son Martin has died from injuries sustained in the attack on Boston. My wife and daughter are both recovering from serious injuries. We thank our family and friends, those we know and those we have never met, for their thoughts and prayers. I ask that you continue to pray for my family as we remember Martin. We also ask for your patience and for privacy as we work to simultaneously grieve and recover. Thank you."
The family had gathered in Copley Square to watch the iconic race, but Bill, a community leader in the Ashmont section of Dorchester, was not running, PEOPLE has confirmed.
Friends of the Richard family gathered Monday night at Tavolo Restaurant, just down the street from Peabody Square, to grieve, according to the Boston Globe.
Michael Dwyer / AP
A neighbor, Jane Sherman, told WCVB that Martin was a typical 8-year-old who loved to ride his bike and play baseball. "There are no words to describe how they are feeling ... we are feeling," she said.
A single candle was lit in front of the family's home, and the word "Peace" was written on the sidewalk in front of it, WHDH said.
The local Dorchester Reporter newspaper said both Bill and Denise Richard were respected as civic leaders in the area.
Bill helped to lead the transformation of Peabody Square over the past decade. The family is said to be deeply involved in Dorchester life, from kids' baseball and soccer to their church, St. Ann's parish in Neponset.
More than 100 people were wounded in the attacks, many of them critically. A massive investigation is underway, under the direction of the FBI.