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A young child remains in critical condition after he fell from a window at an apartment building in Boston's Dorchester neighborhood Wednesday afternoon.

Police said first responders were called to 12 American Legion Highway at 3:17 p.m. for a call that a 4-year-old boy fell out of a fourth-floor window.

Arriving first responders found the child with serious, life-threatening injuries.

"The victim was transported to a local hospital by Boston EMS, where his condition is listed as critical," said Bureau of Investigative Services Supt. Felipe Colon.

"Played basketball outside with my son a lot, so we've seen them around," said John King, who lives next door to the boy. "It's just really unfortunate. It's unfortunate that that happened and my heart goes out to the family."

Erika Moon said her 4-year-old son, Isaac, somehow got around the baby gate in their fourth-floor apartment and managed to open a window.

"He opened the gate that's blocking my window and he opened the window. He leaned out and 'boom,' he fell out the window," Moon said. "I heard the boom, so I went running down and I picked him up. He wasn't breathing."

Neighbors told WCVB they heard a scream, then ran outside to see the boy motionless on the ground

“I heard a scream, and in hearing the scream, I looked out the window. That’s when I saw the child,” said Nelson Peguero. “I don't know them, but I saw a women come out — not sure if it was the child’s mother. She picked up the child and was desperate for help.”

Peguero said the child was not moving after the fall.

“Police patrols arrived. I also went over, but I did not touch anything. First responders arrived. The father, I think it was the father, he was very desperate, screaming,” said Peguero. “I wanted to do something, but I couldn’t because, honestly, it was a very sad situation.”

Suffolk County District Attorney Kevin Hayden, crime scene and homicide investigators were at the scene, police said.

"This investigation will be a joint investigation with the Suffolk County DA's Office, as well as our homicide division, district detectives, and our crimes against children division," Colon said.

Investigators spent Wednesday evening examining the windows on the fourth floor of the four-story brick apartment building.

"He has spectrum autism, so I've been telling the people that we can't be on the fourth floor," Moon said. "He has no sense of danger. He doesn't even speak."

Moon said she is awaiting an update from the hospital regarding her son's condition.

"I just want everybody to pray for him," she said.

Editorial note: Initial information from Boston police described the victim as an infant.

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