By Chris Francescani and Victoria Cavaliere
NEW YORK, March 13 (Reuters) - Search crews picked through still-smoldering rubble on Thursday, looking for survivors of a gas explosion that caused the collapse of two New York apartment buildings a day earlier, killing seven people and injuring about 60.
Facing thick smoke and bitter cold, dozens of firefighters, police officers and a team from the National Transportation Safety Board were at the Upper Manhattan scene to determine what had caused the explosion on Wednesday, shortly after a resident nearby had called utility Con Edison to complain about the smell of gas. The safety board investigates accidents involving natural gas.
The debris continued to flare up at times as rescuers clawed through the rubble of the adjoining buildings that had housed 15 apartments on a largely residential block at East 116th Street and Park Avenue. Passersby wore dust masks or wrapped their faces in winter scarves so as to not breathe in dust and smoke.
Mayor Bill de Blasio said a preliminary investigation indicated the explosion in East Harlem was caused by a gas leak.
Authorities allowed some residents of nearby buildings to return to their homes to retrieve possessions, but many left quickly, complaining of the smoke.
The last time the utility had received a complaint about a gas odor in the neighborhood was in May, said Consolidated Edison Inc spokesman Bob McGee.
At the time, Con Ed had shut the gas off and the building had hired its own contractor to fix a leak. On July 3, Con Ed crews returned to the building to certify the repairs were done correctly, McGee said.
On Feb. 10 and Feb. 28, there were "high speed" checks made of the gas pipes, he said.
De Blasio was briefed by first responders on Thursday morning and said he would hold a press conference later in the day.
Killed in the collapse were four women and three men.
One of the victims was identified as Griselde Camacho, a campus public safety officer for Hunter College in East Harlem, according to a message posted on the school's website. Her age was not given.
About 60 people were injured, most of them from cuts, broken bones and smoke inhalation, police said.
At least three children were among those hurt. Two were treated for minor injuries and released, while a third was in critical condition, hospital officials told a news conference.
The blast leveled the apartment buildings, located above a ground-floor church and a piano store, sending a cascade of twisted and burnt metal on to the sidewalk, burying parked cars.