Source: Christmas Tree Bulb Used in NYC Pipe Bomb

Did it go off prematurely or was it just kind of a dud? The NYPD is still trying to figure that out in the wake of Monday morning's pipe bomb explosion in the New York City subway. Only three bystanders suffered minor injuries in addition to the suspected bomber, who remains hospitalized with more serious injuries. Authorities, however, are clear on one thing: They say the explosion was a deliberate attempt at a terrorist attack on the city. Details and developments:

• Video: Grainy surveillance video captures the moment of the explosion in a crowded subway corridor. See it via YouTube or the New York Times.
• The suspect: He is identified as 27-year-old Akayed Ullah, a native of Bangladesh who lives in Brooklyn, reports the New York Post. Not much is known about him, other than that he held a license to drive a livery cab from 2012 to 2015, per the AP. ABC News reports that he more recently worked as an electrician. He reportedly came to the US about seven years ago on an F-4 visa, which goes to those who have relatives in the US who are citizens. Accounts differ, but he appeared to be living with his parents, brother, and sister.

• The bomb: Police say Ullah attached the bomb to his body with Velcro and zip ties. Described as crude and low-tech, it was apparently homemade. CNN reports that Ullah made it at his (unspecified) workplace, while the AP says he made it at home, quoting Gov. Andrew Cuomo as saying Ullah found the directions online. Police say Ullah strapped it to his torso and had wires protruding from his jacket to his pants. Perhaps ominously, officers say he was reaching for a cellphone before they grabbed his hands.
• More specifically: The New York Times gets much more specific on the device's alleged construction, per sources. They say match heads were stuffed into the pipe, and were ignited when a "Christmas tree light with the bulb broken" was powered on using a nine-volt battery. At least one of the pipe's caps blew off, but the pipe itself didn't blow, and therefore didn't become shrapnel.
• The motive: Unclear. Authorities say Ullah made statements suggesting an allegiance to the Islamic State, though he is not believed to have had any direct contact, reports the Daily News. A pro-ISIS media group posted that the bombing was in retaliation for President Trump's recognition of Jerusalem as Israel's capital, reports the Washington Post.
• Another for NYC: The bombing comes just weeks after a truck attack on a bike lane killed eight people in Manhattan, notes Reuters. It rounds up other attacks in New York City in recent years.
• Rush hour chaos: The New York Times looks at the logistical mess that ensued when the blast shut down what it calls "one of the busiest transit hubs in North America," near rush hour, no less.

(More New York City stories.)