Mark Lennihan / AP
Friday, March 14, 2014 | 2:18 p.m.
NEW YORK — Federal investigators say underground tests conducted in the hours after a deadly New York City gas explosion detected the presence of natural gas.
NTSB team member Robert Sumwalt says the latest information seems to support the hypothesis that the explosion, which killed eight people, was caused by a gas leak.
Sumwalt said Friday that the utility Consolidated Edison dug 50 holes about 18 to 24 inches deep around the blast site and measured gas levels in those cavities soon after the explosion.
He says the gas concentration was up to 20 percent in at least five spots. He says normal levels in New York City soil should be zero.
He says workers have begun the process of pressure testing pipes to identify possible holes.