NEW YORK CITY (WPIX) — A group of religious leaders, anti-violence advocates, and neighbors gathered Friday night in Harlem to mourn the death of 3-year-old Daniel Galeas, who was lost in a tragic accident earlier Friday.

The boy was playing in his grandmother’s apartment Friday morning, jumping on the bed, when he tripped and fell through one of the makeshift, cardboard panel inserts placed on the left side of a window air conditioner, officials said.

Daniel fell four stories out of the rear window and landed in a stairwell that leads to the basement. He was later pronounced dead at Harlem Hospital.

Daniel would have turned 4 on Monday.

Relatives said Daniel and at least three other young cousins and siblings were all inside the bedroom playing under the care of an aunt while the grandmother ran errands.

News of the tragedy spread fast among neighbors. Clergy spent much of Friday evening attempting to attend to Daniel’s grieving family.

Authorities are looking at how the AC was installed, as it was too small for the window and cardboard was used to fill the gap.

By New York City law, all AC units must be safely and permanently installed. Apartments with children ages 10 and under also need to have window guards installed.

Police said the medical examiner will determine the boy’s cause of death.