The incident happened around 2:25 p.m. on the 1800 block of W. Highland Avenue in Milwaukee, the Milwaukee Police Department said.
Police said the 47-year-old man was handling a firearm when it went off and the subsequent gunfire struck the girl. She was rushed to a local hospital, where police said she died of her injuries.
Police did not immediately release the identities of the man or the child.
Police said the death was being investigated as a homicide and that criminal charges would be referred to the Milwaukee County District Attorney’s Office.
An autopsy was scheduled for Monday, the Milwaukee County Medical Examiner’s Office said, adding that no further information will be released at this time.
Milwaukee Acting Mayor Cavalier Johnson released a statement to FOX6 Milwaukee following the child’s death, calling it “heartbreaking.”
“Mistaken gunfire has extinguished another innocent life,” Johnson said. “I offer my condolences to her family. Please, put down the guns. If you have a gun in your home, secure it with a trigger lock or in a safe. Never, never handle a gun near children.”
The child’s death comes just days after Johnson announced a series of proposals to combat the city’s rising crime after a record-breaking year for homicides, with 205 reported killings in 2021, according to the Milwaukee Journal Sentinel.
Other violent crimes Johnson planned to tackle with his proposals included gun violence, car thefts and reckless driving.
Johnson’s plan included bolstering the city’s police force and contributing resources to provide support to the community.
Johnson took over as acting mayor last month after Mayor Tom Barrrett resigned to become the next U.S. ambassador to Luxembourg.