Martin attended the Neighborhood House Charter School.
He "was a bright, energetic young boy who had big dreams and high hopes for his future," the school said in a statement. "We are heartbroken by this loss."
His father, William Richard, released a statement asking people to "continue to pray for my family as we remember Martin."
A neighbor, Jane Sherman, said that the Richard family is a "typical all-American family" and that Martin and his little brother always loved to play in their yard, no matter the weather.
Richard's mother and sister are recovering from serious injuries sustained in the bombing, the father said.
Another life ended: A Boston University grad student
While the name of the third victim killed by the blasts was not officially confirmed on Tuesday, Boston University said that the person was a graduate student at the school.
"The student was one of three friends who watched the race near the finish line," the university said on its website. "Another of the three students, also a BU grad student, was injured and is in stable condition at Boston Medical Center."
The third person in the group was unharmed, the statement added.
A short time later, China's consulate in New York announced that the deceased victim was a Chinese national. At the family's request, the consulate did not name her.
According to a profile on LinkedIn, the woman was a graduate student in mathematics and statistics at Boston University who was due to get her master's degree in 2014.
She graduated from a Chinese university with a degree in international economics, the professional networking site indicated. She'd also previously studied for a semester at the University of California at Riverside.
Chinese students at Boston University respected her family's request for anonymity, with many of them forming a tight-knit group.
One of them, former CNN intern Alex Shi, said that the students are deeply saddened. Many of the students feel affected because people were trying hard to locate those reported missing -- including the victim -- by calling hospitals and posting on social media.