As they waited for further word on the cause, people who felt and heard the detonation said they had been shaken but would carry on with their lives.
"I feel a little bit insecure, but we have to do what we have to do," said Omar León, a real estate investor who was visiting a friend on Saturday night in the building directly next to the blast site.
"There's nothing you can do, really," León said. "You have to read their mind in order to prevent this. Anybody can be around us that has that mentality. Our lives continue."
The explosion, which injured 29 people, rocked the Chelsea neighborhood at 8:30 p.m. By morning, authorities had reopened most streets nearby, but they still blocked off West 23rd Street, where the blast happened. Some subway entrances remained closed.
Gov. Andrew Cuomo told reporters on Sunday that "a bomb exploding in New York is obviously an act of terrorism
," but that there was no evidence tying the blast to known terror organizations.
"We're going to go back to work tomorrow just like we do on any other Monday morning," the governor said.
Several blocks away from the blast site, it looked like an ordinary Sunday morning. People were out getting coffee and walking their dogs. Near the police cordons, people gathered to talk about what they had gone through.
Sam Smith, who lives in the same adjacent building at 135 West 23rd Street, said he had just arrived home on Saturday night and was closing his shades when the explosion struck.
"All I saw was a big light, and then I heard the explosion," he said. "I could feel it in my chest." He said the blast was so powerful that his chest was sore for seven hours, and it took 90 minutes for his hearing to come back.
He said he walked outside in the immediate aftermath and saw "chaos. People running, screaming, a bunch of metal debris in the street."
Smith said the authorities had not told him when he could return home. The 14-story building provides housing and services for the blind, including Smith's sister, who was not home at the time.
"My friend thought it was thunder. I said, that doesn't sound like thunder," said Crissy Holland, who lives a block uptown from the explosion. "It sounded like someone took a barge and threw it all the way off a building."
Wendy Baboolal said she had just arrived in New York from Trinidad and was taking a nap in her hotel room half a block west when the detonation shook her awake.
"I was asleep and it rocked me. I felt it in my chest," she said. "When I looked out the window, I saw people just running."
When Baboolal walked outside, "I saw a lot of people, a lot of cops, the fire people, a lot of ambulances were here," she said. "It was frenzied, people wondering what happened."
A tense calm was restored within minutes as police began closing off nearby blocks and moving onlookers away. People leaving restaurants and a play in the neighborhood stood around checking their phones for news.
Baboolal said she visits New York frequently and sometimes stays with an aunt upstate. But "I love the city, so I wanted to be in the city itself," she said. "I wasn't scared. I love New York so much, so what's the problem?"