Between 60 and 70 percent of rubble has been removed from the site of Wednesday's explosion and collapse, NY1 reported Saturday.
Fire Commissioner Salvatore Cassano said investigators are examining each piece of debris to determine the cause of the explosion.
"We'll take the debris from the area, put it on the sidewalk, examine it before we take it to Randall's Island where the debris will be saved to do a forensic study as part of the investigation," Cassano said.
The National Transportation Safety Board said natural gas was found in the ground below the building during tests after the incident.
"Normally, the soil in New York City 18 to 24 inches down into the ground would have zero concentration of natural gas, so the fact that in least five of the holes, the concentration on gas ranged between 5 and 20 percent, that tells us that's a pretty good concentration of natural gas in that area," said Robert Sumwalt of the NTSB. "That further leads to the hypothesis that this may well have been a natural gas leak."
The NTSB investigation is working to determine the origin of the gas.
Mayor Bill de Blasio said the Real Estate Board is working to find displaced families temporary and long-term housing.
"We made clear to them that we will stand by them every step of the way. We will not let them fall. They've been through the unspeakable. And obviously, we met people who have lost family members and neighbors all in an instant, with no warning. It's our obligation as the city of New York -- I know all New Yorkers feel this way -- to stand by them," de Blasio said.
Meanwhile, an 80-year-old Bible from the Spanish Christian Church, which was destroyed by the blast, was discovered intact by a New York City firefighter, the New York Daily News reported.
The Rev. Thomas Perez was overwhelmed to hear the Bible survived the blast.
"When he saw this Bible, that's when he had the palpitations," city Public Advocate Letitia James said. "Through all of the rubble, through all of the destruction, [the Bible] survived."