More than 30 survivors and their relatives of the 2013 bomb attack on the Boston marathon are running in this year’s race - among them two athletes who are competing on prosthetic legs.
Adrianne Haslet and Patrick Downes are members of the One Fund community, made up of survivors of the attack, their relatives and supporters. A total of 31 are competing in Monday’s 2016 race.
“A lot of people think about the finish line,” Ms Haslet told the Associated Press. “I think about the start line.”
More than 30,000 runners are scheduled to take part in the 120th race.
Mr Downes, 32, was a runner before the bombing, having completed the race in 2005 with his wife, who lost both legs in the attacks.
Ms Haslet, 35, was a professional ballroom dancer who received a prosthetic blade to do the quickstep and the jive, and only then decided to take up running, the news agency said.
Ms Haslet overcame a hip flexor injury while training; running with the blade also required extra energy, because one leg is slightly longer than the other. She is running with a team of four people on behalf of the Oklahoma City-based Limbs for Life Foundation, which provides prosthetics for those who can't afford them.
“It was about finding another challenge, and finding a new day. There was a point in my life I wasn't a ballroom dancer, either,” she said. In 2014 - the first race after the bombing - she completed a short distance of the course with friends.
Defending champion Lelisa Desisa of Ethiopia, who also won in 2013, is running again, along with women's winner Carolina Rotich of Kenya. Defending wheelchair champions Marcel Hug and Tatyana McFadden will also return.
Most of the top Americans will sit out the race, having run in the US Olympic Trials in Los Angeles in February.
The Boston Athletic Association is also commemorating the 50th anniversary of the first woman to complete the Boston Marathon.
The attack was carried out by borthers Dzhokhar and Tamerlan Tsarnaev. Tamerlan was killed while being pursued by police; his younger brother was last year convicted of murder and sentenced to death.
