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A warrant for involuntary manslaughter has been issued against a St. Louis police officer who fatally shot a fellow officer as the two were allegedly playing with a revolver loaded with one round, according to authorities.

Warrants were issued for Officer Nathaniel Hendren, police and the prosecutor said in a statements Friday. Officer Katlyn Alix, 24, was fatally shot sometime before 12:56 a.m. Thursday when she was off-duty at a home in Carondelet with Hendren and another officer, police have said.

This undated photo released by the St. Louis Police Department shows officer Katlyn Alix. St. Louis Police Department / AP

A probable cause statement says that Hendren, 29, and Alix were "playing with firearms when the defendant produced a revolver."

Hendren allegedly emptied the cylinder of the gun and then put one cartridge back into the cylinder, spun the cylinder and pointed the weapon away and pulled the trigger, and the revolver did not fire. Alix took the gun and pointed it at Hendren and pulled the trigger and it also did not fire, according to the probable cause statement.

"The defendant took the gun back and pointed it at the victim pulled the trigger causing the gun to discharge," the probable cause statement reads. Alix was shot in the chest.

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The two on-duty officers rushed Alix to a hospital and called over the radio that an officer had been shot while they were en route to the medical center, where Alix was pronounced dead, Police Commissioner John Hayden said Thursday.

The warrants for involuntary manslaughter and armed criminal action were issued after police reported their initial findings to the Circuit Attorney’s Office, according to police.

Circuit Attorney Kimberly Gardner said in a statement that “this is a devastating incident for Katlyn Alix’s husband, parents, family and for our entire community. Yesterday, we lost a shining star and a dedicated public servant.”

"I have said this many times before; I will hold people accountable who violate Missouri law regardless of their profession, public status or station in life," Gardner said in the statement. "Today, as much as it saddens my staff and me to file these charges, Katlyn and her family deserve accountability and justice."

Police said the warrants were issued "at-large." It was unclear if Hendren planned to surrender or if he has an attorney who could speak on his behalf. Messages to the police union and to the police department were not immediately returned Friday.

The shooting took place at Hendren’s apartment, according to the probable cause statement.

The other on-duty officer with Hendren, who has not been identified, told the pair they should not be playing with guns and reminded them that they were police officers, according to the probable cause statement.

That officer was uncomfortable and left the room, but before he left the apartment he heard a shot and returned to find Alix shot, according to the document.

Alix was with the department for two years, police said. Police said in a statement Thursday that the officer who shot Alix, now identified as Hendren, has been on the force for one year, and the other officer, also 29 years old, has nearly two years of service.

Gardner, the circuit attorney, said in the statement that the charge of first-degree involuntary manslaughter is a felony that carries between 3 and 10 years in prison.

Gardner said at a news conference that it remains an open investigation.