In nearby Medford, William Campbell described his daughter, Krystle, as the light of his life, "a very caring, very loving person."
"Daddy's little girl," the 56-year-old said.
Her mother, Patty Campbell, her voice breaking into tears, said the couple was "heartbroken at the death of our daughter."
"She was a wonderful person. Everybody that knew her loved her. ... She had a heart of gold. She was always smiling. You couldn't ask for a better daughter," the mother said. "This doesn't make sense."
Their daughter's best friend, Karen Rand, suffered a severe leg injury in the blasts. "She's very badly hurt. She's all messed up," William Campbell said. "Her leg was all destroyed."
A friend and co-worker at the restaurant where Krystle Campbell was a manager described her as hardworking yet fun-loving, someone who knew how to live life to its fullest.
"We'd go out drinking and she'd work a double the next day," Sheba Parent said. "But she was still career-oriented and focused on her goals."
Associated Press writers Bob Salsberg, Jay Lindsay and Pat Eaton-Robb in Boston, Katie Zezima in Arlington, Mass., Michelle Smith in Providence, R.I. and Michael Astor in New York contributed to this report.