Outside an apartment building in the Soundview neighborhood of the Bronx, it was a quiet scene Thursday compared to the day before.

At 11:15 a.m. Wednesday, police said a contractor found a newborn baby girl dead in an area down an alleyway towards the rear of the building.

“I had to step out. How could someone do that to a baby?” Luz Quiroz, who has lived in the building on St. Lawrence Avenue for six years, said.

Quiroz said she is the mother of a 10-year-old and a 16-year-old. She said the incident makes her think of her own children at that age.

“We don’t know what happened. We don’t know honestly, so I don’t want to judge no one,” Quiroz said.

“They say the baby was there for three or four days. It was right next to my living room. I could have looked out the window and seen the baby. No one goes there except me or my porter,” Carlos, who declined to provide his last name, said.

The Abandoned Infant Protection Act, enacted in 2000 in New York State, legally allows a parent to leave a baby at a “suitable place,” including a hospital or staffed police or fire station without having to leave their name.

Residents wondered what could prompt a person to leave a newborn alone in an outdoor courtyard.

“It’s really shocking. I don’t even know what to say,” Quiroz said.

Detectives said the newborn did not have any trauma to her body. Police are searching for suspects who may have left the baby.

The cause of death will be determined by the medical examiner.