NEW YORK - A powerful explosion in Lower Manhattan on Thursday caused two buildings to collapse and ignited a large fire that quickly spread to neighboring buildings, leaving at least 19 people injured.
As the fire raged in the East Village neighborhood, there were desperate attempts to flee, with residents jumping from fire escapes, and dramatic rescues, with one man climbing through the smoke to look for people who might have been stranded and others pulling a woman to safety.
The blaze was so intense that firefighters at one point had to withdraw from the buildings and engage in what one official called a "defensive outside attack," pumping a deluge of water onto the structures.
Mayor Bill de Blasio, speaking at a news conference at the scene, said that "preliminary evidence suggests a gas-related explosion" was caused by plumbing and gas work being done at 121 Second Ave.
The explosion and ensuing fire destroyed that building and led to the collapse of an adjacent building, 123 Second Ave.
For hours after the explosion, the fires burned and two other buildings, 119 and 125 Second Ave. were damaged. One of them, 119 Second Ave., was still in danger of collapse, officials said late Thursday.
More than 250 firefighters responded to what became a seven-alarm fire.
Among the 19 people reported injured, three were critically injured; four were firefighters who were taken to hospitals for treatment of minor injuries; and three others, including one emergency medical worker, declined medical attention at the scene, according to the Fire Department.
De Blasio said workers from the utility Consolidated Edison had been on the site about an hour before the explosion and had found the work being done there to be deficient. But the mayor said there were no calls reporting gas leaks before the explosion.
Michael S. Clendenin, a spokesman for Con Edison, said several buildings on Second Avenue had been "undergoing renovations" since as far back as August.
"Based on records here, the building has had some work done inside; new gas service pipes; a lot of things; piping and such," Clendenin said.
The first reports the Fire Department received were for a building collapse, and witnesses described a dramatic scene, with residents of the buildings scrambling down fire escapes to escape the raging flames and others dashing out of the rubble as the walls collapsed around them.
Niraj Desai, 36, a video game animator who works nearby, said he saw one woman stuck on a fire escape struggling to get the ladder unhooked.
"This poor girl was stuck upstairs," he said. "She was having a hard time. You could tell there was a lot of emotion going on. A bunch of guys were down at the bottom helping her get down."
Another man also made his way down the fire escape ladder before smoke started to pour from the building, he said.
"It was pretty crazy, pretty fast," Desai said.
The authorities said that there were no initial reports of people missing and that those who were seriously injured seemed to have been hurt in the explosion.
Residents of five buildings, including the four damaged or destroyed, were unable to return home Thursday night, according to the authorities. The Red Cross established a temporary shelter for them at Public School 63, at 121 E. Third St.
Blake Farber, 29, a film director, said he had smelled a lot of gas and watched as two people who appeared to be working at the site were frantically running between Sushi Park, a restaurant on the ground floor of 121 Second Ave., and the residential entrance.
Seconds later, he said, he felt the blast and was enveloped by dust and smoke.
"And then I saw a bunch of people running out of the restaurant - I saw a man crawling on the ground," he said. "He was crawling and he turned around and his face was bloody."
The blast happened just over a year after a gas explosion leveled two buildings on Park Avenue in East Harlem, killing eight people. Federal investigators found a crack in a Con Ed gas main near the site and a separation between that main and a smaller pipe that led to a building next to the two that were destroyed.
The National Transportation Safety Board has not yet released its final report, which will provide its conclusions about what caused the explosion last March.
On Thursday, the reports of the emergency began with calls to 911, starting around 3:17 p.m. Several callers described hearing an explosion.
Nathan Blaney was at a nearby bar on St. Marks Place when he heard an explosion. His hands still shaking minutes later, he recounted running to the corner and finding about six injured people laid out on the sidewalk.
Blaney took photographs of the wreckage. The facade of the ground floor of the building, which housed Sushi Park, was entirely blown out. Shards of glass reached the sidewalk across the street. Blood was splattered up and down the block and across the street.
One man in a black apron had blood seeping from his head. Several other people were bleeding and covered with dust.
One woman was trapped on the building's fire escape, apparently after climbing out of her apartment, Blaney said. She was stuck on the second floor, afraid to come down.
So a pedestrian - visible in pictures Blaney took - jumped onto the hanging ladder, climbed up and helped her descend to the sidewalk.
At 3:59 p.m. a loud rumble sounded and the lower facade of one of the buildings began moving. A moment later it slid slowly to the sidewalk in a mix of glass and loose bricks.
Heavy gray smoke filled the air, and a few moments later, as the smoke began to lift, it was evident that no part of the building was left standing.
Jordy Trachtenberg was smoking an electronic cigarette on St. Marks Place, trying to calm down after an explosion "rocked his apartment and made him jump" from his chair. Trachtenberg lives at 30 St. Marks Place, which faces the back of buildings on Second Avenue.
"I felt the ground shake underneath me, and then all this debris - plaster and glass - started pelting my windows," he said. "I ran from my building when I saw the flames go up and my apartment filled with smoke," Trachtenberg said. "I couldn't breathe, I started gagging."
"My first thought really was it was my home," he said, "because we haven't had gas for six months, and Con Ed was doing work outside today."
He shouted out to neighbors who passed by, asking them if they were OK.
"Of course I know them," he said. "I want to make sure everyone is OK. St. Marks is the tightest community in New York."