On April 13, 2013, tragedy struck the city of Boston when two pressure cooker bombs exploded near the finish line at the Boston Marathon, killing three and wounding more than 250 others.

Eight-year-old Martin Richard, who'd been watching the race with his parents; Krystle Campbell, 29, a restaurant manager, and Lingzi Lu, a 23 year old Boston University graduate student from China.

Five days following the bombing, MIT campus police officer, Sean Collier was shot and killed during an altercation with the suspects in Cambridge, Massachusetts.

26-year-old MIT police officer, Sean Collier.

Tsarnaev Sentenced To Death

After a long trial and over two years following the bombing, Dzhokar Tsarnaev was found guilty on all 30 counts he was initially charged with. One month after the guilty verdict was announced, U.S. District Judge sentenced convicted felon Dzhokar Tsarnaev to death by lethal injection.

Tsarnaev has become the youngest person on federal death row. The ultimate execution date is not yet set.

One Boston Day

Two years after the bombing, Boston Mayor Marty Walsh announced that April 15, the day of the Boston Marathon bombing, will be known as One Boston Day. Walsh established this day hoping to honor the resilience, strength, and courage of the city.

In a statement released by Walsh, “One Boston Day will inspire all of us to come together as the community we are and share the spirit of Boston by giving back. April 15 is a date that has come to stand for our city’s deepest values. I hope everyone can mark this day in a way that is appropriate and inclusive for each of our experiences.”

Walsh envisions One Boston Day as a day of service and an opportunity for Boston residents to give back to the community.

2014

Boston Strong banners were seen throughout the marathon course.

Boston bombing survivor Celeste Corcoran, center, finished the race with her daughter Sydney, right, and sister Carmen, left.

Heather Abbott, center, crossed the finish line with one of her rescuers, Erin Chatham, left.

One year after the attack, the Boston Marathon drew over 36,000 runners, 8,000 more than the previous year.

2015

Boston Marathon survivor Rebekah Gregory DiMartino crossed the marathon finish line

Boston marathon bombing victims Patrick Downes and his wife Jessica rolled through the finish line two years following the attack. Patrick and Jessica both lost their left legs.

The 2016 Boston Marathon is scheduled on Monday, April 18.