Then, around 8:25 p.m., the 50-year-old's building rattled, the structure shaking with a physical force unlike anything he'd felt since the World Trade Center collapsed on 9/11.
Like Gabrielli, New Yorkers across the city felt as if their home was under siege, and they were confused about why. Here's how the night unfolded, in their own words.
Gabrielli: "[Chelsea] is not like the center of the city -- or the Wall Street area or Rockefeller Center. It's tiny bars, where you go to grab a drink, grab a bite to eat, watch a film."
Ben Brooks, a New York resident who spoke with CNN affiliate NY1: "I was at 22nd [Street] and 7th [Avenue] sitting outside having dinner. It felt like a lightning bolt struck the building. It shook the ground. Everyone ran out of the restaurants into the street. The whole city was in the street."
Gabrielli: "I walked outside toward 23rd Street, between 5th and 6th Avenues."
Ben Von Klemperer, a West Village resident for the past 11 years: "I grabbed my camera and ran out to the scene."
'Should we be scared?'
Gabrielli and his neighbors were among the first to arrive at the explosion site at 23rd Street and 6th Avenue. The streets were surprisingly calm, with few very first responders on the scene. Hours later, investigators believe the explosive device that caused the blast was placed in or near a dumpster, a law enforcement source told CNN. Initially, that wasn't quite clear to passersby in the area.
Brooks: "First, we thought a building collapsed. Then we heard it was an IED."
Gabrielli: "We smelled something, like an intense sulfur smell, and saw smoke coming out of this building. I saw pieces of metal -- not large, but not small either. A few friends of mine saw glass there."
Gabrielli: "Then firemen came from every direction come in. NYPD came from every direction. They blocked the area and pushed us toward 7th Avenue."
David Martinez, one of the people injured in the explosion. He spoke with CNN after being released from the hospital on crutches: "I blacked out, and the next thing you know, I'm in an ambulance."
Von Klemperer: "I arrived about a block away. There were about 10 to 15 people on each corner. No details were being given out. People wanted information. People wanted to know how do I travel and get where they're going? A couple officers were testy."
Brooks: "I've never so many cops driving the wrong way down the street — fire trucks, undercover cops, cops driving aggressively 20 to 30 mph up 7th Avenue. It was definitely controlled. [But] it was aggressive."
Von Klemperer: "One young child asked me, should we be scared? ... I was nervous."
Gabrielli: "The entire neighborhood is real scared. We're worried."
Martinez: "[I'm a] little traumatized. I thought I was close to not actually seeing my son again."
'Something was terribly wrong'
As police and firefighters descended upon the explosion site, another device that's believed to be a pressure cooker was discovered about five blocks south on 23rd Street between 6th and 7th Avenues.
Aiden Leslie, a New York resident who lives a couple blocks away: "I was sitting at my desk, and heard this explosion. ... It was bone chilling."
Ali Faizan, who was visiting with his family on holiday from Pakistan, staying at a hotel located at 27th and Broadway: "I was waiting on 23rd Street outside Best Buy, waiting for my dad to get his dinner, and then I heard this big explosion. It didn't quite feel like those big explosions when you see smoke or fire."
Leslie: "I ran to the scene on 23rd. It was a very chaotic situation. You couldn't see much."
Faizan: "It was just like, poof! It's gone. You could smell gas and gunpowder."
Leslie: "Lots of fire engines. Lots of policeman."
Chenelle Marshall, a 27-year-old New Jersey resident whose car was parked near 27th and Broadway: "We came outside everything was blocked off, a lot of commotion. I hope I don't get a ticket."
Faizan: "Then people were starting to panic. ... They were running out from the [subway] station. There was a busy restaurant on the other side of the street, they were running around too."
Leslie: "I knew in my heart something was terribly wrong."
Faizan: "Then me and my dad just left the area. We got to the hotel. My mother and sister were there. They just got inside, turned on the TV. They were like, 'what happened?'" He described showing his family the explosion site on the news: "That happened."
Leslie: "It's completely unnerving. I was here during 9/11. Living in this state we live, we [must] go about our lives, doing the best we can."
Another eyewitness, who said he also lived through 9/11, was about three blocks away when the blast happened. As an architect, he described the blast in a rather unique way.
Eyewitness: "Well, it sounds like when you hear those metal steel plates, the ones that are like an inch think, 20 foot by 20 foot or 10 foot by 10 foot and it just flattened, fell straight on the ground."
Mazdack Rassi was putting his 2-year-old twin girls to bed at his home on West 27th Street when he heard the explosion.
Rassi: "I went downstairs to see if we should evacuate. They (police) said to go back upstairs. So I started to look out the window and I realized I had a good view of the robot. So I started to Periscope."
Rassi captured video
of a bomb-disposal robot retrieving the suspicious device found on 27th Street, which later turned out to be a pressure cooker, according to law enforcement officials.
'I heard the explosion and I fell'
Ramon Lopez shot video that shows the immediate aftermath of the explosion. In the video, you see a woman with blood on her hands, white pants and shirt, walking shakily. You hear a man speaking to her.
The man: "Come with me, come with me, come with me. I'm holding you. Okay. Come with me. You're okay. Nothing's going to happen. Okay? Nothing's going to happen to you. Come on. There's the ambulance right here. I got you. I got you."
The woman: "I heard the explosion and I fell."
Another woman: "Our friend is around here somewhere. We don't know where she is."