The first bomb went off at about 9:30 a.m. on Saturday, September 17, 2016, in Seaside Park, New Jersey. A pipe bomb detonated inside a trash can on Ocean Avenue, near the starting point of the Seaside Semper Five, a 5K charity run organized for military veterans that was expected to draw as many as three thousand participants. The race had been delayed after someone noticed a suspicious backpack near the course. That delay likely prevented mass casualties; no one was injured. Additional devices wired to the pipe bomb failed to detonate. The race was canceled. By the time investigators arrived, the scene at the Jersey Shore had already become the first thread in a pattern that would stretch to Manhattan by nightfall.

Later that evening, a pressure cooker bomb packed with shrapnel -- small bearings and metal BBs -- detonated in front of 133 West 23rd Street in Manhattan's Chelsea neighborhood. Witnesses described the blast as originating from a sidewalk dumpster near Sixth Avenue, and photographs of the twisted receptacle lying in the middle of the street spread instantly on social media. Thirty-one people were injured, mostly from flying debris and shattered glass. The explosion damaged a five-story brownstone and was captured on three closed-circuit television cameras. A second pressure cooker bomb was found four blocks north, on West 27th Street, concealed in a plastic bag and wired to a mobile phone. Two state troopers discovered it after a resident called police about a suspicious package. The NYPD transported the device to its Rodman's Neck firing range in the Bronx and destroyed it. Surveillance video later showed a man dragging a duffel bag from 23rd Street to 27th Street and leaving it behind.

FBI analysts pulled fingerprints from the undetonated 27th Street bomb and its attached phone, leading investigators to Ahmad Khan Rahimi, a twenty-eight-year-old naturalized U.S. citizen from Elizabeth, New Jersey, originally from Afghanistan. Surveillance footage confirmed Rahimi planting the 23rd Street device and walking to 27th Street with the duffel bag. On the morning of September 19, authorities issued a public alert with Rahimi's photograph. Hours later, a bar owner in Linden, New Jersey, called police after finding a man sleeping in the doorway of his establishment. Responding officers identified Rahimi, who drew a handgun and opened fire. Two officers were wounded before Rahimi was shot and subdued. Evidence showed he had purchased bomb components on eBay between June and August, and investigators believed he had scouted the Chelsea neighborhood before the attack.

Rahimi acted alone but not in a vacuum. Investigators determined his actions were influenced by the extremist ideology promoted by al-Qaeda and the Islamic State, though he was not a formal member of either organization. In October 2017, a federal jury convicted him on all eight counts, including use of a weapon of mass destruction and bombing a place of public use. On February 13, 2018, he was sentenced to a mandatory term of life in prison without possibility of parole. The bombings wounded thirty-three people across three New Jersey and New York locations over a single weekend, yet caused no fatalities -- a fact attributable in part to the delayed start of the Seaside Park race, the crude construction of the devices, and the quick response of bystanders like Parker and White in Elizabeth, who saw something wrong and called it in.

The September 2016 bombings compressed a remarkable sequence into two days. A pipe bomb at a charity run on the Jersey Shore. A pressure cooker in Chelsea. Unexploded devices under a mailbox in midtown and in a backpack at a train station in Elizabeth. A shootout in Linden. Thirty-three wounded, zero killed. The speed of the investigation -- from explosion to arrest in less than fifty hours -- reflected the density of surveillance infrastructure in the New York metro area, the forensic value of unexploded ordnance, and the operational sloppiness of a bomber who left fingerprints on his devices and his face on multiple cameras. For residents of the region, the weekend was a vivid reminder that the threat environment in and around New York City had not diminished since 2001, but also that the city's capacity to respond, investigate, and recover had grown enormously.