Medical workers aid injured people at the Boston Marathon after an explosion Monday. Two blasts shattered the euphoria of the marathon finish line, sending
Medical workers aid injured people at the Boston Marathon after an explosion Monday. Two blasts shattered the euphoria of the marathon finish line, sending authorities out on the course to carry off the injured while the slower runners were re-routed away from the smoking site of the blasts. (Associated Press / The Boston Globe)

BOSTON -- The names Lelisa Desisa and Rita Jeptoo forever will be etched in the books as winners of the 2013 Boston Marathon, but the champions are merely a footnote to history.

Two hours after Desisa, of Ethiopia, and Jeptoo, of Kenya, crossed the finish line to win the men's and women's races, respectively, two bombs exploded there, killing three and leaving more than 130 injured.

With thousands of entrants still on the 26.2-mile course, race volunteers and public officials rushed to the aid of wounded spectators, and the medical tent set up to care for fatigued runners quickly transformed into a trauma clinic.

The explosion sent some runners tumbling to the pavement, while others, already unsteady from the grueling run, were knocked down by those rushing toward the scene. A Rhode Island state trooper who ran in the race estimated he saw at least two dozen people who had lost limbs in the explosion.

Runners and spectators cried as they fled the billowing gray smoke rising from a running-gear store overlooking the end of the course; organizers mobilized to usher the runners still on the course to safety.

The race day started with 26 seconds of silence in honor of the victims of the Sandy Hook Elementary School shooting in December. A little more than two hours later, the lead runners passed the Mile 26 marker, which was decorated with the Newtown, Conn., seal and dedicated to the memory of those killed there.

After another two hours, tragedy and death again befell a New England community.

The stunning event shattered the euphoria of what had been an uneventful 117th edition of the world's oldest and most prestigious annual marathon. Runners still on the course were diverted to the Boston Common; race officials said 4,496 runners had crossed the checkpoint at more than 24 miles but did not reach the finish line.

A year after record high temperatures sent unprecedented numbers of participants to the medical tent, temperatures in the high 40s greeted the field of 23,326 at the starting line in Hopkinton on Monday. The temperature climbed to 54 by the time the winners reached Boston's Copley Square.

Desisa, 23, won a three-way sprint down Boylston Street to finish in 2 hours, 10 minutes, 22 seconds and snap a string of three consecutive Kenyan victories.

In just his second race at marathon distance, Desisa finished five seconds ahead of Kenya's Micah Kogo to earn $150,000 and the traditional olive wreath. Ethiopia's Gebregziabher Gebremariam finished third, and American Jason Hartmann placed fourth for the second year in a row.

Jeptoo, 32, who also won in 2006, finished in 2:26:25 for her first victory in a major race since taking two years off after having a baby.

After a series of close finishes in the women's race -- five consecutive years with three seconds or less separating the top two -- Jeptoo had a relatively comfortable 33-second margin over Meseret Hailu of Ethiopia.

Defending champion Sharon Cherop of Kenya was another three seconds back.

Shalane Flanagan, of nearby Marblehead, was fourth in the women's division in her attempt to earn the first American victory in Boston since Lisa Larsen-Weidenbach in 1985. (An American man has not won since Greg Meyer in 1983.)

Two-time winner Joan Benoit Samuelson, now 55 and running on the 30th anniversary of her 1983 victory, finished in 2:50:29 to set a world record for her age group.

Japan's Hiroyuki Yamamoto was the first winner of the day, cruising to victory in the men's wheelchair race by 39 seconds over nine-time champion Ernst Van Dyk of South Africa. Tatyana McFadden, a Russian orphan who attends the University of Illinois, won the women's race.