Boston Marathon bombing survivor Patrick Downes, center with arms raised, crosses the finish line with his guide and running mates.

Atsede Baysa, left, and Lemi Berhanu Hayle, both of Ethiopia, hold a trophy after they won the women's and men's divisions of the 120th Boston Marathon.

Former Boston Marathon women's division winner Joan Benoit Samuelson, left, poses with her daughter Abby Samuelson, of Portland, Ore., who had just completed the race.

Lemi Berhanu Hayle, of Ethiopia, celebrates after winning the 120th Boston Marathon.

Manuel Cabral, of Canada, kneels on a flag of Portugal, after finishing the marathon.

Atsede Baysa, of Ethiopia, breaks the tape to win the women's division of the 120th Boston Marathon.

Jim Driscoll, left, of Ambler, Penn., and Mitch Kies, right, of Wimberley, Texas, help a runner across the finish line.

Atsede Baysa, of Ethiopia, gets a lift as she celebrates after winning the women's division.

Fans cheer as runners pass Wellesley College during the 120th Boston Marathon.

Tatyana McFadden, of Clarksville, Md., center, winner of the women's wheelchair division of the 120th Boston Marathon, poses with the family of 2013 bombing victim Martin Richard. From left Henry and Bill Richard, McFadden, Denise and Jane Richard.

Boston Marathon bombing survivor Roseann Sdoia stands on her prosthetic legs as runners cross the finish line.

Cutbert Nyasango, of Zimbabwe, douses himself with water as he runs through Wellesley.

Tatyana McFadden, of Clarksville, Md., crosses the finish line to win the women's wheelchair division.

Marcel Hug of Switzerland prepares to accept the first place trophy after winning men's wheelchair division.

Police line the route of the 120th Boston Marathon in Framingham, Mass.

Marcel Hug of Switzerland crosses the finish line ahead of Kurt Fearnley of Australia, center, and Ernst Van Dyk of South Africa, right, to win the men's wheelchair division.

Carlos Arredondo, a 2013 Boston Marathon bombing first-responder, cheers runners on Monday.

Yemane Tsegay, left center, and Deribe Robi, right center, both of Ethiopia, lead the pack of runners just after the start in Hopkinton.

Bobbi Gibb, the first woman to run the Boston Marathon in 1966, waves to the crowd near the finish line Monday.

Defending champion Lelisa Desisa, of Ethiopia, center, runs at the head of the pack.

The men's wheelchair racers leave the start line Monday.

Police muster near the finish line before the start of the marathon.

Boston Marathon bombing survivor Adrianne Haslet, center, poses Monday in Hopkinton, Mass., before running in the 120th Boston Marathon.

An seal honoring 50 years of women running in the Boston Marathon covers the street in front of the start line.

A make-shift memorial dedicated to those killed in the 2013 Boston Marathon bombings adorns a tree near the finish line.