A 3-year-old boy picked up an unattended gun inside a home and it went off, shooting a 1-year-old boy in the head and killing him Sunday afternoon, police said.
Cleveland Police Chief Calvin Williams said investigators are trying to determine where the gun came from.
Emergency workers said the 1-year-old was taken to a hospital and pronounced dead.
Full details about the shooting on the city's east side weren't released, but Williams said at least one adult was home when it happened.
"It's a sad day for Cleveland," he told reporters outside the home. "This fascination that we have with handguns, not just in this city but in this country, has to stop. This is a senseless loss of life."
Cleveland.com reports that the boy's mother could be heard screaming on the back porch after learning her son had died.
Neighbours told the news website the mother lived in the house with at least three small children.
"They were really nice," next-door neighbor Larry Simpson said of the family. "It's a shame this had to happen."