Explosion in New York City’s Chelsea neighborhood: What we know

An explosion in the heart of New York’s Chelsea neighborhood sent dozens to the hospital Saturday night. Shortly after the blast, investigators found a second suspicious device a few blocks away, placing much of the city on edge.

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Authorities know the bombing was intentional, violent and criminal, New York Mayor Bill de Blasio said.

But what we don’t know about the explosion, the mayor said, is just as important.

Here’s the latest, based on details authorities have revealed so far.

What happened in Chelsea?

What we know: Around 8:30 p.m. Saturday night, an explosion occurred at 23rd Street and 6th Avenue on Manhattan’s west side. A law enforcement source, speaking with CNN on the condition of anonymity, said the blast came from an explosive device planted near a dumpster.

Surveillance footage of the explosion, including video from cameras at Orangetheory Fitness in Chelsea, captured bystanders running through the streets, ducking from debris as windows shattered all around.

What we don’t know: Why did the bomb go off in that location? Where did the explosive come from? And who was behind the blast?

How many people were hurt?

What we know: There were 29 victims injured in the explosion. Of those, 24 people went to several local hospitals, including Bellevue Hospital. Armed guards stopped incoming vehicles to the hospital, including ambulances, to make sure none posed a threat to the medical facility.

“Thankfully, none of these are life-threatening injuries and the 24 patients that have been removed are not in serious condition other than the one patient with a puncture wound,” NYPD Commissioner James O’Neill said a press conference.

What we don’t know: Some of the victims closest to the explosion were at a loss for how the blast occurred. This was the case for David Martinez, one of the 29 injured, who said he was “traumatized” after seeing his life flash before his eyes.

“I blacked out, and the next thing you know I’m in an ambulance,” he said.

What’s the latest on the investigation?

What we know: Police have asked members of the public to call in leads, and they’re canvasing the neighborhood for surveillance video that could show who planted the explosive.

They’re also working to determine if there’s any connection between the New York bombing and an explosion that occurred in a trash can near a Marine Corps Marathon route in New Jersey earlier Saturday. Officials told CNN explosives in both incidents apparently used cell phones as timers.

And investigators are looking at another suspicious device that was found blocks away from the New York explosion site: a pressure cooker with dark-colored wiring, according to law enforcement officials.

What we don’t know: So far surveillance videos haven’t pointed investigators toward a suspect, a senior law enforcement official said. Some of the video is not helpful because the cameras are either too far away or the footage is too grainy to tell what’s on it, the official said.

Authorities have found some similarities between the explosions in New York and New Jersey, but they still haven’t concluded they’re connected.

And as for the pressure cooker, investigators haven’t said whether that turned out to be an explosive, or whether it’s related to the New York explosion.

“Think of a jigsaw puzzle out in the street right now,” NYPD Chief of Detectives Robert Boyce said Sunday afternoon. “Do we think they’re related? Yes, we have to move in that direction, but right now we’re not ready to make those calls yet.”

So, what actually caused the explosion?

What we know: Investigators found “some components indicative of an IED” at the explosion site, New York Police Commissioner James O’Neill said.

The explosion was so loud that it reverberated across the Hudson River all the way to Hoboken, New Jersey, according to social media users.

“We smelled something, like an intense sulfur smell, and saw smoke coming out of this building,” said Chelsea resident Danilo Gabrielli. “I saw pieces of metal — not large, but not small either. A few friends of mine saw glass there.”

What we don’t know: At the moment, NYPD has not provided many details about the device responsible for the first explosion.

Who’s responsible?

What we know: No one has claimed responsibility for the blast.

What we don’t know: Officials say they haven’t discovered any connection between the bombing and international terror groups, but they’ve offered different assessments about whether the explosion should be described as terrorism.

“A bomb going off is generically a terrorist activity. That’s how we’ll consider it. And that’s how we will prosecute it,” New York Gov. Andrew Cuomo said.

De Blasio and city law enforcement leaders said more needs to be known about the motive behind the blast before calling it a terror attack.

“We have a lot more work to do to be able to say what kind of motivation was behind this,” de Blasio told reporters Sunday. “Was it a political motivation? Was it a personal motivation? We do not know that yet.”