A 9-year-old boy fell to his death from a window in a Bronx apartment building Sunday afternoon, cops said.

The young boy plunged from the 4th floor of the building at 240 Mount Hope Place at around 4:11 p.m. He was discovered unconscious and unresponsive on the ground, according to police.

The child was rushed by EMS to St. Barnabas Hospital, where he was declared dead.

Initially, cops said the boy fell from the fire escape, but later Sunday night authorities said he fell from a window with an air-conditioning unit.

Police are investigating what led to the tragic fall inside the 6-story building.

A neighbor told reporters near the scene that the victim lived in the building. He said he performed CPR on the child. 

“He don’t come outside like that. He only come from home to school and stuff like that. He just be upstairs,” the neighbor said.

The 9-year-old’s fatal plunge comes after two kids fell from buildings last month on the same day.

A 2-year-old girl fell from the 5th floor of her Queens apartment building on April 17, landing on grass that softened any impact, ABC 7 reported. 

The girl was taken to a local hospital in stable condition.

Earlier that day, a 3-year-old child was critically injured when she fell from the window of the NYCHA Chelsea Houses in Manhattan, the station reported.