Rescuers faced gusty winds, cold temperatures and billowing smoke as they pulled additional bodies out of the rubble overnight and into Thursday evening. The explosion Wednesday morning in East Harlem injured more than 60 people, and searchers are still trying to locate others at the site on Park Avenue and 116th Street.
Crews are using generator-powered floodlights and thermal imaging cameras to identify heat spots, which may indicate bodies or pockets of fire. Huge clouds of thick smoke swirled over Park Avenue and wafted through the neighborhood.
Construction equipment 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.
The fiery blast erupted at about 9:30 a.m., around 15 minutes after an area 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.
Investigators believe a gas leak triggered the explosion. Authorities told ABC News the ignition source may be a heating unit or hot water boiler in the basement. However, the fire department and Con Edison said a check of its records found no instances in the past 30 days in which tenants of the two buildings reported gas odors or leaks.
The blast 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.
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 National Transportation Safety Board team arrived Wednesday 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.
The Associated Press contributed to this report.