Searchers continue to comb through the rubble of the collapsed apartment buildings in New York searching for more survivors after a suspected gas leak demolished the building on Wednesday and killed at least seven people there.

It is reported that a caller called in to the Con Ed gas Utility at 9:13 am, moments before the explosion that rocked the east Harlem neighborhood. Utility workers, in two trucks, arrived at the scene after the explosion had already taken place. The caller reported that they had smelled a gas odor the night before but failed to call it in. Others said that the odor of gas was reported to the landlord on Tuesday.

Other tenents report that the city’s fire officials were contacted about the smell of a gas leak weeks ago, but the fire department says that it has gone through its records and they show no sign of calls coming in reporting a gas leak at that location.

Workers toiled through the night amid smoke, cold temperatures, that ranged in the 20s, and gusty winds and rain, to search through the rubble. Their efforts would discover four more dead in the carnage.

Seven people are confirmed killed in the explosion and ensuing collapse of the buildings. Another 70 were injured in the neighborhood disaster. Another five people are still missing.

The National Transportation Safety Board, who investigate pipeline accidents as well as transportation disasters, has responded to the scene, and NTSB officials say that they will investigate how the utility handles reports of gas odors and leaks and will construct a timeline of events as well, in an effort to determine the cause of the explosion.

Since the blast, the city of New York has experienced a doubling of calls reporting the smell of gas throughout the city. Yesterday, at least 90 calls were made reporting gas odors.