2013 Boston Marathon Bombing

On Patriots' Day, April 15, 2013, two homemade pressure-cooker bombs were detonated near the finish line of the Boston Marathon, striking one of the city's most beloved annual traditions and sending shockwaves across the nation. As runners from around the world were cheered by thousands of spectators lining the streets for the 117th Boston Marathon, two self-radicalized brothers, Tamerlan and Dzhokhar Tsarnaev, executed what the FBI described as the largest terrorist attack on U.S. soil since 9/11, detonating two powerful explosives near the finish line and killing three people while injuring more than 500 others. The attack, which unfolded on Boylston Street in the city's Back Bay neighborhood, triggered a multi-day manhunt that brought Greater Boston to a standstill and resulted in one of the most intensive law-enforcement operations in American history.

Background and Setting

April 15, 2013, marked the 117th running of the Boston Marathon, the world's oldest annual marathon. The popular event is held on Patriots' Day, which commemorates the 1775 battles of Lexington and Concord that kicked off the Revolutionary War. The festive atmosphere draws hundreds of thousands of spectators to the 26-mile 385-yard (42,195-metre) route from Hopkinton, Massachusetts, to Boston's Back Bay neighbourhood, and more than 26,000 runners participated in the race in 2013.

There were 26,893 official entrants, and more than 500,000 people gathered along the marathon route to cheer on those runners and celebrate Patriots' Day, the Massachusetts state holiday. The race's finish line on Boylston Street, flanked by tens of thousands of spectators, was the most densely crowded section of the course when the bombs were detonated that afternoon.

The Bombing

At 2:49 p.m., the first of two bombs was detonated at 671 Boylston Street; the second bomb was detonated thirteen seconds later 180 yards up course at 755 Boylston Street. It was later determined that the explosions were caused by homemade improvised explosive devices (IEDs) hidden in backpacks and placed on the ground level in these viewing areas just seconds before they were detonated.

It was revealed that the devices used in the attacks were household pressure cookers that had been packed with an explosive substance, nails, and ball bearings—the latter two elements acting as shrapnel when the bombs detonated.

The bombs killed Martin Richard, age 8; Krystle Campbell, age 29; and Lu Lingzi, age 23, and injured 264 others. More than 500 people were physically injured in total, including 17 who suffered amputations. The immediate aftermath on Boylston Street was chaotic. Following the explosions, emergency responders — police, fire, and EMS — along with Boston Athletic Association medical volunteers from the Alpha Medical Tent and numerous spectators and bystanders quickly responded to the critically injured, triaging their injuries and facilitating their transport to area hospitals.

In all, 281 people were injured in the bomb blast according to data from the One Fund Boston, and were cared for at 26 hospitals. Within 1½ hours of the initial event, 78% of the patients treated at trauma centers had already arrived.

The Suspects and the Manhunt

On April 18, the Federal Bureau of Investigation released images and video of two men identified as suspects in the attacks, including one photograph that showed one of the men placing a package at the location of the second explosion. The suspects were quickly identified as brothers Tamerlan Tsarnaev, age 26, and Dzhokhar Tsarnaev, age 19.

At the time of the bombings, Dzhokhar Tsarnaev was a sophomore at the University of Massachusetts Dartmouth and Tamerlan Tsarnaev, a former amateur boxer, was married and had a young child. The brothers were Muslims, born in the former Soviet Union republic of Kyrgyzstan in 1986 and 1993. Investigators concluded that the Tsarnaevs planned and carried out the attack on their own and were not connected to any terrorist groups.

On April 18, 2013, at 10:25 p.m., the Tsarnaev brothers ambushed and shot Sean Collier of the Massachusetts Institute of Technology Police Department six times. The two brothers were attempting to steal Collier's sidearm, which they could not free from his holster because of its security retention system. Collier, aged 27, was seated in his police car near Building 32 on the MIT campus and died shortly after the shooting.

The terrorists then carjacked a vehicle, kidnapped its driver, and forced him to drive to a gas station, robbing him of $800 along the way. After the driver escaped, the terrorists drove to Watertown, Massachusetts, where they detonated several improvised explosive devices. Shortly after midnight, police in the Boston suburb of Watertown spotted the suspects and tried to apprehend them. A gun battle broke out on a Watertown street, with the Tsarnaevs exchanging fire with the police and hurling explosive devices at them. Tamerlan Tsarnaev was fatally wounded during the Watertown firefight.

Much of Greater Boston came to an unprecedented standstill as officials requested that residents remain in their homes and that businesses not open. The "stay home" order was lifted at 6:00 pm on April 19, when a Watertown resident went to his backyard to check on a boat parked there, noticed that its protective tarp had come loose, and, while adjusting it, observed Dzhokhar Tsarnaev hiding in the boat. Police soon arrived, and after a short standoff Tsarnaev was taken into custody.

Investigation

The investigation that followed the bombing was one of the largest law-enforcement undertakings in the city's history. FBI Boston's Evidence Response Team (ERT) — working with teams from the Boston Police Department, the Massachusetts State Police, and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) — spent nine days processing 12 square blocks near the bomb scenes. About 176 FBI Laboratory and ERT personnel were deployed to Boston to assist, and evidence technicians processed more than 3,500 pieces of evidence and shipped 2,749 items to the Laboratory in Quantico, Virginia, for further analysis.

More than 33 terabytes of digital information were collected, including photos and video from the public via a special digital tip line developed to support the investigation. Linguists spent more than 2,500 hours translating material to support the investigation and trial.

Ultimately, more than 20 law enforcement agencies with more than 1,000 investigators joined the investigation, according to a Boston Globe account. Prior intelligence was also scrutinized: before the bombing, Russian officials had asked the FBI to look into Tamerlan Tsarnaev's possible ties to extremists, but police in Boston were not told.

Trial, Sentencing, and Legal Aftermath

In July 2013, Dzhokhar Tsarnaev pleaded not guilty to the 30 federal charges against him, including the use of a weapon of mass destruction resulting in death. He was found guilty by a jury of all 30 charges on April 8, 2015, and was sentenced to death by lethal injection. At his trial, he apologized to survivors and family members of the victims.

Tsarnaev's death sentence was later overturned by a federal appeals court on grounds of possible jury exposure to media coverage and exclusion of evidence, but in March 2022 it was reinstated by the U.S. Supreme Court. After hearing arguments in United States v. Tsarnaev, the Court upheld the death penalty, reversing the First Circuit Court's decision on March 4, 2022.

Memorialization and Legacy

The attack left a deep mark on the city of Boston and on the broader national consciousness. Shortly after the bombing, people from all over the world began leaving objects and messages of support at the police barricades that surrounded the bombing site. Once the scene was cleared and the barricades were removed, these objects and messages were moved to Copley Square where even more were added.

On April 15, 2014, the mayor of Boston and the governor of Massachusetts hosted a ceremony honoring the marathon bombing victims along with the first responders on the scene. In the years since, memorials have been established throughout the Boston area. These include dedications in memory of the victims across Massachusetts, including the Martin Richard Institute for Social Justice at Bridgewater State University.

BPD Sgt. Dennis "DJ" Simmonds, age 28, from Randolph, MA, died on April 10, 2014, as a result of a severe head injury caused by an explosion set off by the bombers during the confrontation in Watertown on April 19, 2013. His sacrifice, along with that of MIT Officer Sean Collier, has been commemorated through multiple memorial dedications around the region.

The bombing also prompted significant changes in mass-event security protocols nationally and internationally. The bombing set in motion refinements in how FBI Boston prepares for critical incidents, from pre-determining a staging area for evidence collection to the precise roles every last field office employee will have in the event of an incident. The attack is remembered every year at the Boston Marathon with moments of silence observed at the finish line on Boylston Street.