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.