New York (CNN) -- A day before investigators expected to gain full access to the site of a deadly explosion that leveled two New York buildings, firefighters digging through the rubble found an intact Bible belonging to the evangelical church that once stood there.
Fire Commissioner Salvatore Cassano told reporters that by Sunday, investigators expected to reach the piping and gas meters in the basement at the scene of Wednesday's blast in East Harlem that killed eight people and injured dozens others.
Natural gas might have triggered the explosion that shook the vibrant neighborhood, federal officials said. The National Transportation Safety Board could start pressure-testing gas pipes in the area on Sunday, Cassano said.
On the third day of a grueling recovery effort from the three-story pile of rubble, firefighters early Saturday pulled a large waterlogged Bible from the ashes and ruins of the Spanish Christian Church, which occupied the basement and first floor of one of the two destroyed buildings.
"One of our members found a Bible, the original book they tell me of the founders of the church," Cassano said. "It was singed, but it meant an awful lot to the pastor because at least we have a remnant of the church. It showed the pastor they'll be rebuilding. This church is resilient."
When firefighters presented the Spanish-language Bible to the church's 83-year-old pastor, the Rev. Thomas Perez, the pastor was overcome.
Perez, who has stood vigil with others at the blast site, was participating in a small prayer gathering with religious leaders and experienced chest pains, said the Rev. Vernon Williams, who attended the vigil.
Cassano said Perez was recovering at Lenox Hill Hospital in Manhattan's Upper East Side.
"He was overwhelmed with emotion, for sure," the fire commissioner said. "It's a very sacred thing for him."
After Perez was taken away by ambulance, Williams said, about two dozen people at the vigil prayed for him before carrying the Bible in a procession near the site.
"It was the altar Bible," Williams said. "There was no singing on the Bible at all. It was intact, with a little water damage."
The small evangelical church and Bethel Gospel Assembly lost five members in the explosion.
The blast victims were identified as Carmen Tanco, 67; Alexis (Jordy) Salas, 22; Griselde Camacho, 44; Rosaura Hernandez, 21; Andreas Panagopoulos, 43; George Ameado, 44; and Rosaura Barrios, 44.
Though it is still possible other victims could be found, police said Saturday that only one known victim has not been publicly named.
"We've recovered all the people that were reported missing, but we're still looking through the debris and a couple of areas in the back in case somebody was there, Cassano said.
The ordinary rhythms of the vibrant East Harlem neighborhood of corner bodegas, botanicas, churches, shops and redbrick tenements were shattered with the Wednesday morning blast.
Said Cassano, "We're doing our best to get through as much of the debris as we can as quickly as possible and try to bring some normalcy back to the neighborhood."
CNN's Adrienne Zulueta contributed to this report.