"He was just having a ball, splashing in every puddle," Cunningham said.
The victim's father Bill Richard released a statement Tuesday afternoon thanking family, friends and strangers for their support following his son's death Monday. Richard's wife Denise and 6-year-old daughter Jane also suffered significant injuries in the blasts.
"My dear son Martin has died from injuries sustained in the attack on Boston," it 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."
Other neighbors and friends remembered Martin as a vivacious boy who loved to run, climb, and play sports including soccer, basketball and baseball.
The Richard family were watching Monday's race, and had gone to get ice cream before returning to the area near the finish line before the blasts.
"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 Congressman Stephen Lynch, a friend of the family for 25 years.
He said they are a strong family and are doing better than expected, while rallying around the 6-year-old girl.
Lynch said the family was attempting to get over the race barriers and into the street when the second blast occurred, killing Martin. Bill Richard and the older brother, Henry, were not seriously injured, but doctors did remove ball bearings from Bill Richard's leg, Lynch said.
"Ball bearings are meant as anti-personnel munitions," he said. "They were trying to cause carnage here."
On Tuesday morning, candles burned on the stoop of the family's single-family home in the city's Dorchester section, and "peace" was written in chalk on the front walkway. A child's bicycle helmet lay overturned on the front lawn.
"What a gift. To know him was to love him," longtime friend Judy Tuttle said of Martin, who remembered recently sitting at the dining room table having tea with Denise Richard while the boy did his homework. "He had that million-dollar smile and you never knew what was going to come out of him. Denise is the most spectacular mother that you've ever met and Bill is a pillar of the community. It doesn't get any better than these people."
Neighbor Betty Delorey, 80, said Martin loved to climb the neighborhood trees and hop the fence outside his home.
"I can just remember his mother calling him, 'Martin!' if he was doing something wrong," she said. "Just a vivacious little kid."
Delorey had a photo showing Martin dressed as the character Woody from the Toy Story films, wearing a cowboy hat, a sheriff's badge, jeans and a big smile. His sister, Jane, was at his right dressed as Woody's friend, Jesse. Their older brother, Henry, was to their left, dressed as Harry Potter.
"I'm sick to my stomach," she said. "It's hard to say anything really."
The children's father, Bill, is a leader in a local community group, and an avid runner and bicyclist.
Denise Richard works as a librarian at the Neighborhood House Charter School, where Martin was a third-grader and Jane attends first grade.
Counselors were being made available Tuesday to staff and students, according to school spokeswoman Bodi Luse, who said the whole community was devastated.
"I just can't get a handle on it," Cunningham said of the boy's death. "In an instant, life changes."
Associated Press writers Jay Lindsay and Pat Eaton-Robb contributed to this report.
Restaurant manager identified as bombing victim
A 29-year-old restaurant manager has been identified as one of three people killed in the bombing at the Boston Marathon.
Her father says Krystle Campbell, of Medford, Mass., had gone with her best friend to take a picture of the friend's boyfriend crossing the finish line on Monday afternoon.
William Campbell says his daughter, who worked at a restaurant in nearby Arlington, was "very caring, very loving person, and was daddy's little girl." He says the loss has devastated the family.
He says the friend was seriously injured in the explosion. An 8-year-old, Martin Richard of Boston, also died. He was at the finish line watching the race with his family.
The Associated Press