The bodies of newborn twin boys have been discovered wrapped in brown paper on a patio in the Bronx area of New York City.
Authorities suspect the babies were hurled from a window in the building.
The building superintendent found the infants on Monday afternoon behind the Claremont high rise and informed a resident of the grim discovery, who called the police.
One baby had a puncture wound that may have occurred during birth, while the other had a head injury and a blue string wrapped around his neck.
Blood splatter could be seen on the ground where the infants were found, which is in an area not accessible to non-residents.
Officers are still canvassing the area for information and surveillance footage in an attempt to identify the babies’ parents.
Osvaldo Volquez, the building resident who called police, said he saw one baby “curled up in the foetal position” alongside what looked like a placenta.
“I could see its little hands and feet,” the 72-year-old told the New York Post.
He said the child was fully formed and did not seem to be alive when he arrived on the scene.
“It is a terrible act of humanity,” he said. “I don’t know who would do such a thing.”
Local landlord Mohammed Oumarir, 70, said: “It shouldn’t be that way for nobody, even the animals.”
Neighbour Cassandra Bell, 52, said: “It’s f****d up because they could have gave them kids to somebody that don’t have kids.
“This is the Bronx. But that shouldn’t have happened to them babies.”
NYPD Deputy Chief Timothy McCormack has asked for the public’s help with the investigation.
He said whoever left the infants could face charges of disposing human remains, and possibly other charges depending on what the babies’ cause of death is determined to be.