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 the director of 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, said Bodi Luse, a school spokeswoman.
"We are devastated," she said. "The whole community is devastated."
Cunningham remembered running in a community 5K race with the Richard family on a rainy day years ago. He said Martin would jump out of a stroller that his mother was pushing to hop in the mud puddles along the route.
"I just can't get a handle on it," he said of the boy's death. "In an instant, life changes."