BOSTON — Third-grader Martin Richard had just gotten ice cream and was near the Boston Marathon finish line, eagerly watching for friends to run by. Krystle Campbell was enjoying the race with her best friend, hoping to get a photo of the other woman’s boyfriend after he conquered the last mile.
Then the unthinkable struck. The spirited 8-year-old, pictured on Facebook in his classroom holding a sign that read ‘‘No more hurting people,’’ was dead, along with the outgoing 29-year-old woman and a graduate student from China — victims of twin bombs that turned a scene of celebration into chaos.
More than 170 others suffered injuries that included severed limbs, shrapnel wounds and abdominal lacerations.
Jeff Bauman Jr., a man pictured in an Associated Press photo being rushed from the scene Monday in a wheelchair, lost both legs. Rescuers took the 27-year-old to Boston Medical Center, where doctors found extensive vascular and bone damage.
‘‘Unfortunately my son was just in the wrong place at the wrong time,’’ his father, Jeff Bauman, wrote in a Facebook post.
The younger Bauman, who had been at the race to cheer on his girlfriend, had further surgery because of fluid in his abdomen.
‘‘I just can’t explain what’s wrong with people today, to do this to people,’’ the father wrote. ‘‘I’m really starting to lose faith in our country.’’
While mourning the dead Tuesday, friends and neighbors tried to focus on positive memories of cherished ones whose deaths still seemed unreal to them.
‘‘I just can’t get a handle on it,’’ said Jack Cunningham, a longtime friend of little Martin and his family. ‘‘In an instant, life changes.’’
Cunningham recalled how, as a pint-sized preschooler, the boy had insisted on getting out of his stroller during a 5K race in South Boston. As soon as his mom let him out to run with the rest of the family, Martin took off along the rainy race course.
‘‘He was just having a ball, splashing in every puddle,’’ Cunningham said.
The boy’s father, Bill Richard, released a statement thanking friends, family and strangers for their support following his son’s death.
Richard’s wife, Denise, and the couple’s 6-year-old daughter, Jane, suffered serious injuries in the blasts. Their older son, Henry, wasn’t hurt. Two neighbors said Jane lost one of her legs in the attack.
‘‘My dear son, Martin, has died from injuries sustained in the attack on Boston,’’ Richard said. ‘‘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.’’
U.S. Rep. Stephen Lynch, a family friend, said Martin and his family were trying to get over the race barriers and into the street after the first blast, when the second bomb struck.
‘‘They were looking in the crowd as the runners were coming to see if they could identify some of their friends when the bomb hit,’’ said Lynch, who has known the Richards for 25 years.
Bill Richard, a runner and cycling enthusiast who did not run the race, had to have several ball bearings removed from his leg, Lynch said.
On Tuesday, a candle burned on the stoop of the family’s single-family home in the city’s Dorchester section, and the word ‘‘Peace’’ was written in chalk on the front walkway. A child’s bicycle helmet lay overturned near the front lawn.
At a nearby park, ‘‘Pray for Martin’’ was written in large block letters on the pavement.
Next-door neighbor Betty Delorey said Martin loved to climb trees and play sports with his brother and sister and the other children in the neighborhood.