The heartbroken mother of a 3-year-old boy who plummeted to his death Sunday night from a 13-story window in Harlem prayed and sobbed as paramedics desperately tried to save him, witnesses said.

The little boy, Latyr Sene, fell from the window in a building in the Harlem River II Houses on Frederick Douglass Blvd., near W. 151st St. at 7:12 p.m., officials and horrified witnesses said.

“I heard a bang and I looked out the window, and he was just laying there on the ground,” said an upset Annette Aiken, 47, who was in a friend’s apartment on the ninth floor when tragedy struck.

“It was very loud and I thought the air conditioner fell, but it wasn’t the air conditioner. It was the boy hitting the air conditioner on the way down.”

Aiken screamed out a window, “The baby fell out the window, the baby fell!”

She and her friend ran outside and saw the panicked mom rushing to her child’s side.

“When she got down here she was trying to see him, bending down trying to see him. She was really distraught.”

Aiken said the victim had a twin brother, whom the mother clasped tightly.

“She was by (the fallen boy),” she said. “She was doing her prayers and held her other son tight. She held him real close. She was very distraught. Every one out here was very upset about this.”

Aiken said the mom is a devout Muslim who always covers her face and hair. She didn’t know her name, or the boy’s, but described the mother as “very nice, very friendly.”

“She’s very religious and always had her kids with her,” said Aiken. “She’s a good mother.”

Charles Cabbell, 65, who lives across the street, was walking home from a deli when a movement caught his eye.

“I saw something coming down,” he said. “I thought they threw some trash out the window at first, but then I heard the slam. I went over there and saw that there was a baby on the ground.

“From that fall, a 3-year-old baby, his bones are fragile. He couldn’t have made it. He’s just a little baby. He’s not going to get a chance to go to school or any of that.”

A window guard lay on the ground near the boy’s body.

EMTs were on the scene within minutes and Aiken witnessed them taking the lifeless boy and his mother into the ambulance. Minutes later, the mother left the ambulance in tears.

“She came back out and she was on the ground, holding the gate and crying,” Aiken said. “She was very distraught, barely able to stand up. They must have told her he didn’t make it.”

The boy was taken to Harlem Hospital.

Late Sunday, the child’s parents briefly returned to the home with family members and then left again for the NYPD’s 32nd Precinct stationhouse.

“My parents, they’re holding her,” the victim’s uncle Sohibu Thian said of his grieving sister. “This is tough.”

Police said the tragedy is still under investigation and they were looking into why the window guard fell to the ground.

NYCHA does not have a record of the boy or his parents being residents of the building, according to sources familiar with the investigation.

State law requires property owners to have working window guards where children age 10 or under reside, and tenants must inform the owners if young kids live there.