NEW YORK (NYTIMES) - A four-year-old boy was thrown to his death from his seven-storey apartment building in Brooklyn by his 20-year-old brother early on Saturday (Sept 29), police said.

Officers responded to a 911 call at 3.30am about an unconscious child on Nostrand Avenue in the East Midwood neighbourhood and found the boy, Shimron Smith, unresponsive in a rear courtyard.

He was pronounced dead at the scene.

The brother was taken into custody and was expected to be charged in connection with the boy's death, police said.

Officers blocked access to the courtyard on Saturday afternoon. One section of the fire escape leading to the roof was blocked by police tape and guarded by two officers.

Neighbours described Shimron as a sweet boy they often saw running and laughing on his way to or from school.

"He was always smiling, always laughing and running, like the average four-year-old," said Nicole Pierre, 30, an occupational therapist who has lived in the building for 22 years. "That's why this is so sad."

Pierre said she heard the news when she was trying to return home early on Saturday and could not get into her building.

"It shocked me to my core," she said.

The older brother was described by numerous neighbours as mentally unstable. Multiple neighbours said they never saw Shimron with the brother.

Neighbours talked about Shimron and his brother in disbelief as they heard the news.

Around 12.30pm, a neighbour from across the street came with a bouquet of flowers.

He placed the flowers in front of the building, paid silent respect and then wiped tears from his face before walking off.

"May God Rest Your Soul Shimron Smith," read a card attached to the flowers.