A 9-year-old girl was killed by gunfire during a reported brawl in downtown Trenton Friday night, according to authorities. No one has been arrested in the shooting that occurred around 7:30 p.m. at Kingsbury Square, according to a press release from the Mercer County Prosecutor’s Office. Police responded to the area after receiving reports of fights breaking out among a large crowd, as well as Shot Spotter activation for possible gunfire. They saw a large group of people outside in a courtyard and found the girl suffering from a single gunshot wound, the prosecutor’s office said. First respon…