Brothers Tamerlan and Dzhokhar Tsarnaev detonated homemade bombs twelve seconds and 210 yards apart near the marathon's finish on Boylston Street, killing 8-year-old Martin Richard, Krystle Campbell, and Lingzi Lu. A massive manhunt followed, locking down Boston and culminating in Tamerlan's death in a shootout and Dzhokhar's capture hiding in a backyard boat four days later.
The bombing struck at 2:49 p.m., roughly four hours into the race, when the crowd near the finish line was thickest with runners completing the course and families cheering them on. The blasts, built from pressure cookers packed with nails, ball bearings, and low-grade explosives, were designed to maximize shrapnel injuries; seventeen victims lost limbs.
What followed was one of the largest manhunts in American history. Investigators used marathon security footage and bystander photos to identify the brothers within days. A shootout in Watertown killed an MIT police officer and left Tamerlan dead after his younger brother ran him over while fleeing. Boston entered an unprecedented lockdown—'Shelter in Place'—as thousands of law enforcement officers searched door to door until Dzhokhar was found hiding in a dry-docked boat in a resident's backyard. He was later convicted and sentenced to death, a sentence upheld by the Supreme Court in 2022.
Key people: Tamerlan Tsarnaev, Dzhokhar Tsarnaev