A 4-year-old boy died Monday after falling four stories from an apartment window in Brooklyn, police said.

The child fell from the fourth-floor of the building at 3301 Farragut Road in East Flatbush just before 3 p.m., cops said.

First responders rushed him to NYC Health + Hospitals/Kings County, where he died, according to police.

What caused the boy to take the tragic tumble wasn’t immediately clear.

Police sources said the fatal fall appeared to be an accident, and that no criminality was suspected.