The body of an adult male was pulled from the rubble just after midnight local time, the fire department said. He was pronounced dead at the scene.
A gas leak triggered the explosion yesterday morning on Park Avenue and 116th Street in East Harlem, Manhattan. The blast also injured more than 60 people, at least three of them children.
Authorities say the fiery blast erupted about 15 minutes after a neighbouring resident reported smelling gas. The Con Edison utility said it sent workers to check out the report, but they did not arrive until it was too late.
One of the three people killed was identified as a security officer at a Manhattan college. Hunter College president Jennifer Raab said Griselde Camacho had worked there since 2008.
Another victim was identified as a dental hygienist and cousin of a television news cameraman.
A police spokeswoman identified the victim as 67-year-old Carmen Tanco. Ms Tanco's cousin, News 12 cameraman Angel Vargas, said his family started a frantic search after she failed to show up for work yesterday.
The explosion shattered windows a block away, rained debris on to elevated commuter railway lines close by, cast a plume of smoke over the skyline and sent people running into the streets.
Fire officials said some people were unaccounted for but cautioned they might not have been in the buildings.
Edward Foppiano, a Con Edison senior vice president, said there was only one gas odour complaint on record with the utility from either address, and it was last May. It was a small leak in customer piping and was fixed, he said.
The block was last checked on February 28 as part of a regular leak survey, and no problems were detected, Mr Foppiano said.