A would-be suicide bomber detonated a pipe bomb strapped to his body in the heart of Manhattan’s busiest subway corridor, rending the early Monday commute with a blast that reverberated up through the city’s sidewalks, caused transit chaos, and terrified thousands of travelers who fled headlong through tunnels choked with smoke.

He chose the location because of its Christmas-themed posters, recalling strikes in Europe against Christmas markets, he told investigators, and set off his bomb in retaliation for U.S. airstrikes on ISIS targets in Syria and elsewhere, several law enforcement officials said.

But his makeshift weapon sputtered. The attacker himself was the only one seriously injured, reports the New York Times.

A suspect, identified by the police as Akayed Ullah, 27, an immigrant from Bangladesh who lived in Brooklyn, was in police custody. He suffered burns to his hands and abdomen, and was at Bellevue Hospital Center, according to Daniel A. Nigro, the commissioner of the New York Fire Department. Three other people had minor injuries, he said.

Ullah acted alone, Mayor Bill de Blasio said, adding that no other devices had been found.

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