Investigators are hoping to find clues as to what caused the deadly explosion at two New York City apartments as they reach the basement levels of the buildings. 

Emergency crews have cleared most of the debris allowing NTSB investigators access to the buildings gas lines and meters. 

Eight people were killed and dozens more injured in the explosion early Wednesday in East Harlem. 

Fire officials said everyone has been accounted for and there is no reason to believe anyone else is missing.