St. Louis, MO – Prosecutors announced on Friday that St. Louis Officer Nathaniel Hendren, 29, is being criminally charged for the shooting death of Officer Kaitlyn Alix, 24, on Thursday.

Soon-to-be former Officer Hendren is being charged with first degree involuntary manslaughter and armed criminal action.

St. Louis Post-Dispatch reports that, Officer Alix was off-duty when she went to Officer Hendren’s home.

On-duty Officer Hendren and his unidentified on-duty partner met Officer Alix shortly after night shift roll call to socialize.

While at the house, Officer Hendren grabbed a revolver that was not a department-issued weapon. He removed all of the bullets and then put one back in, according to the probable cause statement.

Officer Hendren spun the cylinder, pointed the gun away, and pulled the trigger. The gun didn’t fire.

Officer Alix then took the gun, pointed it at Officer Hendren, and pulled the trigger. The gun didn’t fire.

The unidentified partner of Officer Hendren told investigators that he reminded the two that they were police officers, shouldn’t be playing with guns, and he wanted no part of it. He says he started to leave when Officer Hendren took the gun and pulled the trigger while it was pointed at Officer Alix’s chest.

The gun went off, striking Officer Alix in the chest.

The on-duty officers sent out an “officer in need of aid” alert, and rushed Officer Alix to St. Louis University Hospital, where she was pronounced dead, the St. Louis Post-Dispatch reported.

While at the hospital, Officer Hendren headbutted the back windshield of a police SUV, breaking it, according to the St. Louis Post-Dispatch. He remains hospitalized for his injuries.

The investigation into the fatal shooting is ongoing.

Officer Alix served as a military police officer before she joined SLMPD in 2016, according to the St. Louis Post-Dispatch.

Her mother, Aimee, told KMOV that Officer Alix enlisted in the Army because she wanted to follow in her older brother’s footsteps.

“Katie enlisted when she was 17,” Aimee said. “I signed for her because that’s what she wanted to do. She was following in her brother’s footsteps because he did the same.”

She was also deployed to Cuba during her military service, her mother said.

Officer Alix graduated from the police academy in January of 2017, and was assigned to the department’s Sixth District, the St. Louis Post-Dispatch reported.

She was working as a patrol officer with the Second District at the time of her death.

“Officer Alix was an enthusiastic and energetic young woman with a bright future ahead of her,” Chief Hayden said Thursday in a press release.

“On behalf of the Metropolitan Police Department, I extend my deepest sympathies to the Alix family during this extremely difficult time,” the chief continued. “I ask the St. Louis community to keep the Alix family and the entire Metropolitan Police Department in your thoughts and prayers as we mourn this tragic loss.”

Aimee said her daughter “loved her job,” and that she often went to the station even when she wasn’t on duty, KMOV reported.

“She would go visit her friends down there because…when you’re a police officer, [you have] that close bond with everyone,” she said.

Officer Alix leaves behind her husband, parents, and sister, according to the St. Louis Post-Dispatch.