On Sunday, thousands participated in the Run to Remember—Boston’s first major road race since the bomb attacks at the Boston Marathon.

Samantha Herwig, of Salem reacted while crossing the finish line of the Run to Remember. Herwig, who ran the Boston Marathon, said she ran the last 6 miles of the Marathon with her friend who didn't get to finish, and today she was running for her.

Jennifer Bresnahan of Arlington, left, and Maureen Spencer of Lowell celebrated after crossing the finish line.

Members of the 31st Massachusetts Transit Police Academy crossed the finish line.

Christie Matlellan of Weymouth and Larry Harmon of Stoughton wore Boston Strong shirts to the race.

People ran with flags during the race.

Madeleine Pascolini, right, a member of the MIT Outing Club, who was friends with fallen MIT Police Officer Sean Collier, crossed the finish line.

MIT EMS member Kat Goldsmith, left, who knew fallen MIT Police Officer Sean Collier ran in his honor.

Elizabeth Mahoney, of South Weymouth, center, was escorted across the finish line by a member of the Boston Police Department SWAT Team.

Kyric Avery of Arlington, left, and Jenny Ahn of Somerville embraced after crossing the finish line.

Runners took to the street at the start of the Run to Remember.

Boston Police Commissioner Edward Davis addressed a crowd of runners at the start of the Run to Remember.

The back of a runner's shirt had the word, “Thanks.” taped to the back of it.

Justine Lescarbeau, left, who ran the Boston Marathon, celebrated with Kayla Michaela as they crossed the finish line.

Lauren O'Keefe of Boston wore a homemade “Collier #179” tag on her back in memory of fallen MIT Police Officer Sean Collier. Although O'Keefe did not know Sean Collier she was running in his memory.

Members of the MIT Outing Club, who were friends with fallen MIT Police Officer Sean Collier chatted before the start of the race.

Some runners wore American-flag socks during the race.

The annual Run to Remember, ­organized by the Boston Police Runner’s Club, raises money for everything from running shoes for city youths to treadmills for local police departments.

Kathy Finneran, of Braintree, clasped her hands as bagpipers played “Amazing Grace” before the start of the race.

Participants received a finisher’s medal.

Bibs were given to each participant to honor Officer Collier.

Members of a Chicago police running team met with Boston.com’s Elizabeth Comeau.