Rescuers seek survivors of NY building collapse; seven dead

New York City firefighters work at the site of a building explosion and collapse in the Harlem section of New York, March 12, 2014. REUTERS/Brendan McDermid

NEW YORK (Reuters) - Search crews picked through still-smouldering 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 fire-fighters, 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 the utility, Con Edison, to complain about the smell of gas. The safety board investigates accidents involving natural gas.