NEW YORK (RNN) - A sixth person was reported dead Thursday in the Harlem explosion that caused two buildings to collapse, fire department authorities confirmed, and at least 60 were injured.
Bodies were recovered from the disaster site early Thursday morning. As of Wednesday night, at least nine people were missing.
New York's Hunter College identified one of the victims as Sgt. Griselde Camacho, a safety officer at the school. In a statement, President Jennifer J. Raab called her a "well-liked member of our community, a respected officer and a welcoming presence."
Cold temperatures overnight could complicate efforts, with temperatures expected to reach the 20s, according to the Associated Press.
Authorities have said a gas leak caused the blast that took down the adjacent business and residential buildings.
A spokesman for National Transportation Safety Board investigators who arrived at the site said the type of pipeline supplying natural gas to the buildings was a concern for his team.
NTSB board member Robert Sumwalt said in an evening press conference the distribution line responsible for the gas leak was made of cast iron.
Natural gas line accidents fall under the agency's jurisdiction, and cast iron lines have raised enough red flags that the NTSB has had discussions about them before.
"We've had a longstanding concern about cast iron pipes," Sumwalt said. "Just this morning we had a briefing where we talked about an explosion in Birmingham, AL, that involved cast iron pipe, and there was an explosion in Allentown, PA three years ago."
The first and most recent of the explosions Sumwalt referenced crushed and burned a 40-year-old woman in a two-story apartment complex in Alabama's largest city in December 2013. The pipe was installed in the early 1950s.
Five bodies were found in an explosion in Allentown, almost three years to the day of the New York explosion. A recently born baby was among the fatalities. Close to 50 buildings were damaged, and hundreds of people were evacuated.
Sumwalt said his team of four NTSB investigators had not been able to get close enough to the site to check for causes of the explosion. The investigation could last as long as one year, but they can make emergency recommendations at any time prior.
New York Mayor Bill de Blasio said in a news conference there were a number of people still missing. Firefighters were digging through debris, which included bricks, wood and metal to find other victims.
Smoke could be seen pouring from the building, and the FDNY has more than 250 members and 44 units with special equipment. They have been extinguishing the fire and doing search and rescue.
"It sounded like a bomb went off, so everyone started screaming, 'They blew up the Metro North!' But when we got there, we saw it was the building and started pulling people out," said Denise Ortiz, who was at a nearby doctor's office when the building collapsed.
Emergency responders began receiving 911 calls at 9:31 a.m. ET.
Spanish Christian Church and a piano repair shop were on the first floor of 1644 Park Avenue, which is no longer standing. There were no outstanding violations or work orders, according to NBC New York.
"We've never had anything like this happen in my community … for some time," Rep. Charlie Rangel, D-NY, told NBC New York.
Metro North trains were halted due to debris on the tracks.
"Out of an abundance of caution, we are temporarily suspending service to look for debris on the tracks," railroad spokesman Aaron Donovan told the Journal News.
According to Con Edison's Twitter feed, a gas odor was reported at 9:13 a.m. by a resident from a nearby building. Two crews were dispatched at 9:15 a.m. and arrived shortly after the explosion. The company has been shutting off gas lines in the neighborhood as the recovery effort continues.
According to Associated Press, Ruben Borrero, a tenant in one of the destroyed buildings said that residents had complained to the landlord about the smell of gas as recently as Tuesday, a day before the disaster.
A few weeks ago, Borrero said, city fire officials were called because the odor was so bad that a tenant on the top floor opened the door to the roof for ventilation.
The neighborhood has contiguous buildings with many mom-and-pop shops on the first floor and residential dwellings above them.
In May 2012, an unoccupied five-story building at 110 West 123rd Street collapsed in Harlem. No one was injured, according to CNN.
Copyright 2014 Raycom News Network. All rights reserved.