They were standing near the finish line, cheering the runners in the Boston Marathon. It was a beautiful, cool day when two bombs unleashed chaos and killed three people. Friends of those killed say they are devastated by the senseless deaths.
Here is some of what we know about each of the victims:
Krystle Campbell, 29, Arlington, Massachusetts
"She was the best," Campbell's distraught mother, Patty, told reporters on Tuesday. "You couldn't ask for a better daughter."
The family is heartbroken and still in shock, Patty Campbell said as she tried to read a statement on the family's porch.
Everyone loved Krystle, she said.
"She had a heart of gold. She was always smiling," Patty Campbell said as her son, Billy, clutched her with his right arm.
Krystle's grandmother said the 29-year-old was a special kind of person who nurtured deep friendships.
"Oh, she was a beautiful girl," Lillian Campbell told CNN's Jake Tapper. "She was very happy, outgoing, a hard worker."
Lillian Campbell said her granddaughter even lived with her for a year and a half and was "great with me."
Her granddaughter was always willing to help someone in need, she said.
"And she was, she was just beautiful. She was a fun-loving girl," Campbell said.
Krystle Campbell once worked at Summer Shack, a seafood restaurant in the Boston area that posted a statement on its Facebook page saying she was beloved.
"She was an incredible woman, always full of energy and hard at work, but never too tired to share her love and a smile with everyone," the post said. "She was an inspiration to all of us. Please keep her and her family in your thoughts and prayers."
According to the Boston Globe, Campbell had taken a job with Jimmy's Steer House in Arlington.
The Globe reported that Campbell often went to the see the marathon runners.
"She's been doing it since she was a little girl," Lillian Campbell told the newspaper. "She didn't miss a marathon, watching it at the finish line."
Campbell was a 2001 graduate of Medford High School, the town's mayor, Michael McGlynn, said.
CNN affiliate WHDH reported that the Campbells are longtime residents of Medford.
Martin Richard, 8, Dorchester, Massachusetts
Like many young boys in New England, Martin Richard loved his Boston Red Sox and the Bruins.
"He wore his (Red Sox second baseman) Dustin Pedroia shirt to school last week," neighbor Bill Forry told CNN's Anderson Cooper.
Martin was a terrific athlete, too, Forry said, but he was also a very good student who would help others who were having trouble with homework.
"A quiet kid, but a compassionate kid -- and somebody who was a leader," Forry said.
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.
