Volker Fischer had just crossed the finish line when the first bomb exploded behind him, sending dark smoke into the air on that fateful day in downtown Boston.
Luni Tiongson was about two blocks beyond the finish line, retrieving her gear and preparing to meet her husband, Ron, who had finished the race about a half-hour before her.
Cynthia Garcia had just passed the 26-mile marker.
"I could see the finish line. Then all of a sudden I heard a big boom," said the Chicago-area resident. "I just kept running."
Despite the horrific events that ruined what was supposed to be a triumphant day filled with celebration a year ago Tuesday, these runners and scores of others are returning to Boston next week for the city's annual marathon. They are going not only to compete in one of the most renowned races in the world, but to honor the victims and first responders from the tragedy last year.
About four hours into the 2013 Boston Marathon, two pressure-cooker bombs exploded near the finish line on Boylston Street, killing three people and injuring 264 others. Two men who turned out to be brothers were suspected of the attacks. One was killed in a shootout with police. The other was arrested and is awaiting trial.
"There were so many people injured that day who have kept going," said Garcia, 53, who is returning to Boston to fulfill a lifelong dream of completing the race. "They have inspired me to keep going."
The 2014 marathon has drawn about 36,000 registered runners, the maximum that organizers allow for the race and 9,000 more than last year's total.
Among the local runners will be those who a year ago were forced to stop before the finish line as well as those who completed the 26.2-mile course but want to race again to show their solidarity with Boston.
"Going back is like an itch you have to scratch. You have to get it done," said Glen Ellyn resident Sandi Borgman, who a year ago finished about 30 minutes before the first bomb went off. "You just want to go back and honor those who can't."
For JoAnn Cassell, this year's marathon is about unfinished business.
The St. Charles resident plans to kiss the ground at the end of the race. Then she'll put a flower down at the spot where one of the victims, an 8-year-old boy named Martin Richard, was killed last year.
"Running a marathon is not only a physical effort but also a mental effort," Cassell said. "I think knowing that this is not even half as hard on me as it was on the people who got hurt last year will push me harder to finish stronger."
While some runners -- like Vernon Hills Village Trustee Michael Marquardt -- didn't hesitate when registration opened for this year's marathon, others took pause.
"I wasn't going to go, and then when it was the deadline, I decided I really wanted to go back and be part of the race again," said Angie Dudman, of Geneva. Last year, Dudman was waiting for a few friends who were still running the race when the first bomb went off.
Most runners who were stopped before the finish line didn't have their cellphones. For some families, it took hours to reconnect.
"When we have the physical and mental exhaustion of actually running a marathon, and then something like this happens, it adds to the confusion that the runner might already have just from being in the race and then not being able to find loved ones," said Michele Kerulis, a sports psychology consultant at the Adler School of Professional Psychology. "It's terrifying."
After the first bomb exploded, Fischer saw people running toward the smoke to help, he said.
In that moment, he thought of his friend who also ran the race but a bit faster. They had plans to walk to another friend's house a few blocks away for a post-race beer.
"I remember thinking, 'It's a great idea to keep moving, but which direction should I go?'" said Fischer, who eventually connected with his friends.
This year's Boston Marathon will be Fischer's seventh, and he's not scared to return.
"We can't let those guys dictate our actions," he said.
Kerulis, director of the Adler Schools sport and health psychology program in Chicago, said that when athletes experience traumatic events, their resilience and perception of what happened will dictate how they cope and how quickly they bounce back.
For some, like Fischer, their dedication to the sport and to their peers is enough to rise above any emotional turmoil.
But for others, the "what ifs" and survivor's guilt can take hold of their feelings, making it difficult to overcome the trauma.
"It's just the fact that they had a different reaction and they're not ready to be exposed to that environment yet," Kerulis said.
The idea of what could have happened to Analy Ponce-Villarreal and her husband last year is enough to keep her away from Boston next week.
The West Chicago woman remembers almost giving up with a mile left. When she pressed on and limped across the finish line, her husband watched from the sidelines with other spectators. Six minutes later, the first bomb exploded near where her husband had stood.
She wonders what would have happened if she had walked the last part of the race.
"I am thankful to God that I did not walk that last mile, because he would have been in those stands. That's where I told him to be," said Ponce-Villarreal, 37. "I didn't find him for some time. It was a bad experience."
And when she does return, she doubts she'll let any of her family members join her.
"You don't go to a race feeling like that," Ponce-Villarreal said. "I want to go back when I'm ready to run and enjoy it and not be there thinking about my experience from last year, because then I'm going to have a bad marathon."
Naperville cardiologist Jim Ostrenga also said he gets emotional thinking about what could have been, but there was no doubt he'd return to the Boston Marathon after being stopped about six blocks short of the finish line last year.
If Ostrenga, 63, had been feeling better and running at his normal pace, it's likely he would've crossed the finish line just before the bombs went off. His wife would have been there too, waiting with the crowd to see him finish, but a broken leg kept her in the hotel room that day.
This year's race, he said, "is going to be a healing experience for the city and the runners and the country." But even with the bombings fresh in his mind, he isn't concerned about security.
Nor is Maria Schreiber, a mother of three from La Grange.
She heard the explosions near the finish line of last year's race.
After calling her husband and texting her father -- "bomb ... I'm OK" -- Schreiber, 50, navigated the crowded streets back to her hotel.
"I have complete faith in the organizers and in all the cities leading up to Boston, all of the communities involved all along the course," she said. "I have complete faith in them; they're ready."
Still, next week's return to Boston will probably stir up emotions, Luni Tiongson said.
"You know, this is what we love to do," she said. "Boston has been a very good city for us. For us, it's a way to celebrate life too."
Tribune reporters Lolly Bowean, Jonathan Bullington, Melissa Jenco, Greg Trotter, Quan Truong, Wes Venteicher and Dan Waters contributed.