NEW YORK - Rescuers working amid cold, gusty winds and billowing smoke pulled four additional bodies overnight from the rubble of two Manhattan apartment buildings, as the death toll rose Thursday to at least seven from a gas leak-triggered explosion that reduced the area to a pile of smashed bricks, splinters and mangled metal.
The explosion Wednesday morning in East Harlem injured more than 60 people, with searchers still trying to locate others a day later. Mayor Bill de Blasio said Thursday that the city was "hoping to find others still alive" and then "to determine exactly what happened here."
Earlier, he told firefighters at the scene, "I can only imagine knowing that at any moment you might find a body, how difficult that is."
Crews used generator-powered floodlights and thermal imaging cameras to identify heat spots - bodies or pockets of fire - at the site on Park Avenue and 116th Street. Police guarding the scene wore surgical masks and neighborhood residents covered faces with scarfs amid the thick, acrid air.
Edward Kilduff, the Fire Department's chief of department, said the amount of debris had been reduced to about 1½ floors by Thursday morning. He said rescuers were concerned about the stability of a free-standing wall at the back of the scene.
Huge clouds of thick smoke swirled over Park Avenue and wafted through the neighborhood.
Construction equipment with iron jaws picked up the smoldering debris, first depositing it on the pavement, then hoisting it onto trucks that hauled it away. The debris included structural beams, pieces of windows and residents' belongings.
Workers initially were hampered from fully accessing the building space because of a sinkhole caused by a subsurface water main break. The weather also posed a challenge, with temperatures dropping into the 20s and rain falling overnight.
The fiery blast erupted around 15 minutes after a neighboring resident reported smelling gas, authorities said. The Con Edison utility said it immediately sent workers to check out the report, but they didn't arrive until it was too late.
Fire Commissioner Salvatore Cassano and Con Edison CEO John McAvoy said that before that call, they had received no complaints in the last 30 days about a gas leak in the area.
The explosion shattered windows a block away, rained debris onto elevated commuter railroad tracks close by, cast a plume of smoke over the skyline and sent people running into the streets.
"It felt like an earthquake had rattled my whole building," said Waldemar Infante, a porter who was working in a basement nearby. "There were glass shards everywhere on the ground, and all the stores had their windows blown out."
Hunter College identified one victim as Griselde Camacho, a security officer who worked at the Silberman School of Social Work building. Hunter said Comacho, 45, had worked for the college since 2008.
Also killed was Carmen Tanco, 67, a dental hygienist.
Mexican officials said two of the victims came from the country's central state of Puebla. Authorities in Puebla identified them as Rosaura Barrios Vazquez, 43, and Rosaura Hernandez Barrios, 22.
New York City Police had put Hernandez Barrios' age at 21. The Puebla authorities did not say whether the women were related.
The bodies of three unidentified men also were pulled from the rubble, authorities said.
At least three of the injured were children; one, a 15-year-old boy, was reported in critical condition Thursday with burns, broken bones and internal injuries. A woman was in critical condition with a head injury. Most of the other victims' injuries were minor and included cuts and scrapes.
A tenant in one of the destroyed buildings, Ruben Borrero, said residents had complained to the landlord about smelling gas as recently as Tuesday.
A few weeks ago, Borrero said, city fire officials were called about the odor, which he said was so bad that a tenant on the top floor broke open the door to the roof for ventilation.
"It was unbearable," said Borrero, who lived in a second-floor apartment. "You walk in the front door and you want to turn around and walk directly out."
The Fire Department said a check of its records found no instances in the past month in which tenants of the two buildings reported gas odors or leaks.
Jennifer Salas lived in one of the buildings. She told The New York Times that her husband, Jordy Salas, and their dog were in the building at the time of the collapse and were missing.
"Last night it smelled like gas, but then the smell vanished and we all went to sleep," she said.
Salas' family continued to hold out hope Thursday that he'd be found alive.
His father-in-law, Jorge Ortega, told The Associated Press that the 21-year-old was last seen Wednesday morning when he returned from his night job at a Bronx restaurant.
Ortega said his distraught daughter, whom he identified as Jennifer Mendoza, is six months pregnant.
Edward Foppiano, a Con Ed senior vice president, said there was only one gas odor complaint on record with the utility from either address, and it was last May, at the building next door to Borrero's. It was a small leak in customer piping and was fixed, he said.
The block was last checked on Feb. 28 as part of a regular leak survey, and no problems were detected, Foppiano said.
One of the side-by-side buildings had a piano store on the first floor, the other a storefront church.
City records show that the building Borrero lived in was owned by Kaoru Muramatsu, proprietor of the piano business. A phone number listed for Muramatsu rang unanswered.
Records at the Department of Housing Preservation and Development indicate the agency responded to complaints from a tenant and cited Muramatsu in January for a broken outlet, broken plaster, bars over a fire escape, a missing window guard and missing carbon monoxide and smoke detectors.
City building records don't show any work in progress at either address, but the building owned by the Spanish Christian Church had obtained permits and installed 120 feet of gas pipe last June.
Con Ed said it remains to be seen whether the leak was in a company main or in customer-installed inside plumbing. The gas main that serves the area was made of plastic and cast iron, and the iron dated to 1887, Foppiano said.
"Age is not in and of itself an issue with cast iron," he said, noting that Con Edison has a cast iron replacement program and the pipe was not slated to be removed in the next three-year period.
A National Transportation Safety Board team arrived in the evening to investigate. The agency investigates pipeline accidents in addition to transportation disasters.
NTSB team member Robert Sumwalt said investigators would be looking at how Con Edison handles reports of gas odors and issues with the pipe and would be constructing a timeline of events.
Just before the explosion, a resident from a building next to the two that were destroyed reported smelling gas inside his apartment and thought the odor might be coming from outside, Con Ed spokesman Bob McGee said.
On Wednesday night, the American Red Cross served meals to more than 130 people living in seven buildings impacted by the blast. The Salvation Army provided accommodations in one of its shelters.
The explosion destroyed everything Borrero's family owned, including the ashes of his father, who died a few years ago. Borrero said he assumes his 5-year-old terrier, Nina, was killed.
But "I have my mother and sister," he said. "I'm happy for that."