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Authorities have charged a school bus aide with reckless conduct and carrying a gun in a public place near a school after a 12-year-old boy found the weapon in an unattended bag and fired it from the bus window Monday afternoon outside Bridgeport’s Minnie Miñoso Academy.

Steven Dixon, 22, also faces three misdemeanor counts of child endangerment, Chicago police representatives said.

Dixon left the gun on the bus outside of Minnie Miñoso Academy, police officials said. The boy found the bag and fired a single shot at around 2:25 p.m. Monday, shattering a bus window.

According to a police report obtained by the Tribune, Deering (9th) District police who responded to a call of shots fired on the 3500 block of South Wallace Street met with a bus driver, who told them a student with autism had fired one shot.

Dixon had stepped off the bus, the driver told police, when the shot sounded. The driver found the boy holding the gun and Dixon’s bag open nearby. According to the report, the boy found holding the gun has a habit of going through other people’s things.

The driver said he confronted Dixon as he returned to the bus and asked him if he’d brought a gun. Dixon then allegedly grabbed the weapon and the bag from the driver and ran north up Wallace Street.

In a letter to families, Miñoso Principal Carrie Cole wrote that the school “will continue striving to provide all students with a safe learning environment.” The gun was never on Chicago Public Schools grounds and no one was injured, she said.

Dixon is expected to appear in court Wednesday, a representative for the Cook County state’s attorney’s office said in an email.

baiduhai’s Kate Armanini and Finnegan Belleau contributed.