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Rescuers continued to search Thursday morning for nine people unaccounted for after a deadly building explosion in northern Manhattan triggered a 5-alarm fire and collapse.

Crews pulled four bodies from the rubble late Wednesday night amid bone-chilling weather and blustery winds, raising the death toll to at least seven. The explosion Wednesday morning in East Harlem injured more than 60.

Generator-powered floodlights and thermal imaging cameras were used 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.

"This is a difficult job, a challenging job," Fire Department spokesman Jim Long said. He said it was "a very terrible and traumatic scene."

Workers were initially hampered from 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, but workers remained at the site. The New York Post reported nine people are still believed to be missing.

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The fiery blast erupted at about 9:30 a.m., 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.

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.

"I saw the building fall. It just fell down. I thought it was a bomb," African Market owner Magatte Samb told The Post. "I felt like I was going to die."

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Hunter College identified one victim as Griselde Camacho, 45, a security officer who worked at the school. Also killed was Carmen Tanco, 67, a dental hygienist. Police identified another victim as Rosaura Hernandez-Barrios, 21.

The bodies of four unidentified people also were found. A man was pulled from the rubble just after midnight, a woman found at about 2:50 a.m. Thursday and a man discovered about a half-hour later. Fire Department spokesman Danny Glover didn't immediately know the gender of the seventh person, whose body was pulled from the rubble around 7:30 a.m.

At least three of the injured were children; one, a 15-year-old boy, was reported in critical condition with burns, broken bones and internal injuries. Most of the other victims' injuries were minor and included cuts and scrapes.

An off-duty police officer and two FBI agents in the area on unrelated business suffered injuries. No firefighters, medics, or other responders were hurt, MyFoxNY.com reported.

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,

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. Con Ed said there was only one gas odor complaint on record 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, the utility said.

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.
  
A National Transportation Safety Board team arrived in the evening to investigate. The agency investigates pipeline accidents in addition to transportation disasters.
     
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.