Nearly 24 hours later, police remain at the scene trying to piece together what happened.
It happened on 77 Prospect Street just after 7 p.m. on Sunday at a 12th-floor high-rise.
"I believe an uncle was pleading with police, trying to get back there and see.I believe the father came around and he was desperately looking for his son, saying that. And he ended up going to the hospital with his wife," resident Julian Gittens said.
Police have not released the child's name.
Investigators say a language barrier with the family has made the sensitive investigation more challenging.
What detectives know so far is that three adults were in the apartment at the time.
The apartment window was open and the screen was in place; the screen could not prevent the tragedy.
"I do know that in Stamford, unlike say New York City, we do not have a building code that requires safety bars on windows," Sgt. Sean Boeger said.
"The kid is 4 years old. How did he open the window? How did he climb up? He's got to be like this big. But I don't want to make any judgments because right now I am sure the parents are probably so distraught because that has to be the worst thing that could ever happen," resident Joe Silvers said.
While police do not suspect any sort of foul play, the unanswered questions haunt the boy's neighbors.
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