New York - Rescue workers using dogs and thermal-detection gear to search rubble for more victims of a gas explosion found an eighth body on Thursday while investigators tried to pinpoint the leak and determine whether it had anything to do with the city's ageing gas and water mains, some from the 1800s.
At least five people were unaccounted for after the deafening blast on Wednesday morning destroyed two five-story East Harlem apartment buildings that were served by an 1887 cast-iron gas main. More than 60 people were injured.
Fire and utility officials said that if the buildings were plagued in recent days or weeks by strong gas odours, as some tenants claimed, they have no evidence anyone reported it before Wednesday.
National Transportation Safety Board team member Robert Sumwalt said the gas main and distribution pipe under the street had been examined in a crater and were found to be intact, with no obvious punctures or ruptures. They had not been torn from the ground, he said.
However, he said NTSB investigators had been unable to conduct a fuller examination because of the rescue effort underway, and it was unclear whether the leak came from inside or outside the buildings.
He said there had also been a water main break at the site, but it was unknown if that contributed to the gas explosion or was caused by it. The water main was installed in 1897, according to the city.
Authorities also hoped to reach the basement - still under rubble - to examine heating units, meters and other equipment that might hold clues to the blast, fire department Commissioner Salvatore Cassano said.
"We can only get conclusive evidence when the fire is out, when the rescue is completed, and we really get a chance to look at all the facts," said Mayor Bill de Blasio.
Ageing infrastructure - crumbling bridges, highways, water mains and gas lines - has become a major concern in recent years, especially in older cities in the Northeast, and has been blamed for explosions, floods and other accidents.
"We know this is a fundamental challenge for New York City and any older city," de Blasio said. But he said the federal government needs to provide more aid to cities to deal with the problem.
Officials said workers were about 40% to 50% through the rubble, using sound devices and putting telescopic video cameras into small voids to see if there is someone in there.
Police identified four of the dead: Griselde Camacho, 45, a college security officer; Carmen Tanco, 67, a dental hygienist who took part in church-sponsored medical missions to Africa and the Caribbean; Andreas Panagopoulos, a musician; and Rosaura Hernandez, 22, a restaurant cook from Mexico.
Mexican officials said a Mexican woman, Rosaura Barrios Vazquez, 43, was among those killed.
The bodies of two unidentified men were also pulled from the rubble.