Jennifer Salas lived in one of the buildings. She told The New York Times that her husband, Jordy Salas, and their dog were in the building at the time of the collapse and were missing.
"There's six floors in the building; each floor has one apartment," she said. "Last night it smelled like gas, but then the smell vanished and we all went to sleep."
Salas' family continued to hold out hope Thursday that he'd be found alive.
His father-in-law, Jorge Ortega, told The Associated Press that the 21-year-old was last seen Wednesday morning when he returned from his night job at a Bronx restaurant.
Ortega said his distraught daughter, who is six months pregnant and whom he identified as Jennifer Mendoza, went to the hospital Wednesday but was resting at his home on Thursday.
Ortega said Jordy Salas' father was up all night waiting for any news.
Edward Foppiano, a Con Ed senior vice president, said there was only one gas odor complaint on record with the utility from either address, and it was last May, at the building next door to Borrero's. It was a small leak in customer piping and was fixed, he said.
The block was last checked on Feb. 28 as part of a regular leak survey, and no problems were detected, Foppiano said.
One of the side-by-side buildings had a piano store on the first floor, the other a storefront church.
City records show that the building Borrero lived in was owned by Kaoru Muramatsu, proprietor of the piano business. A phone number listed for Muramatsu rang unanswered.
Records at the Department of Housing Preservation and Development indicate the agency responded to complaints from a tenant and cited Muramatsu in January for a broken outlet, broken plaster, bars over a fire escape, a missing window guard and missing carbon monoxide and smoke detectors.
City building records don't show any work in progress at either address, but the building owned by the Spanish Christian Church had obtained permits and installed 120 feet of gas pipe last June.
Con Ed said it remains to be seen whether the leak was in a company main or in customer-installed inside plumbing. The gas main that serves the area was made of plastic and cast iron, and the iron dated to 1887, Foppiano said.
"Age is not in and of itself an issue with cast iron," he said, noting that Con Edison has a cast iron replacement program and the pipe was not slated to be removed in the next three-year period.
A National Transportation Safety Board team arrived in the evening to investigate. The agency investigates pipeline accidents in addition to transportation disasters.
NTSB team member Robert Sumwalt said investigators would be looking at how Con Edison handles reports of gas odors and issues with the pipe and would be constructing a timeline of events.
Just before the explosion, a resident from a building next to the two that were destroyed reported smelling gas inside his apartment and thought the odor might be coming from outside, Con Ed spokesman Bob McGee said.
On Wednesday night, the American Red Cross served meals to more than 130 people living in seven buildings impacted by the blast. The Salvation Army provided accommodations in one of its shelters.
The explosion destroyed everything Borrero's family owned, including the ashes of his father, who died a few years ago. Borrero said he assumes his 5-year-old terrier, Nina, was killed.
But "I have my mother and sister," he said. "I'm happy for that."
Associated Press writers Julie Walker, Verena Dobnik, David B. Caruso, David Crary, Leanne Italie, Meghan Barr and Mike Casey contributed to this report.
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