The off-duty St. Louis cop who was accidentally shot in the chest and killed by an on-duty officer early Thursday was identified by the department as 24-year-old Officer Katlyn Alix.

Chief John Hayden said two on-duty officers, both 29, had stopped by one of their homes during their shift, though it was not clear which officer's home it was. Alix also stopped by the home. One of the on-duty officers "mishandled" a gun and accidentally shot Alix in the chest while they were in the living room of the home, according to a report.

"This is a tragic situation," St. Louis Circuit Attorney Kim Gardner said in a statement, adding that she was asking for help from the Missouri Highway Patrol to conduct an investigation into Alix's death.

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“The family of Officer Alix deserves a complete, objective and thorough investigation of this incident," Gardner's statement continued. "My office is approaching this criminal investigation with the highest level of seriousness and urgency.”

"This is a tragic situation. The family of Officer Alix deserves a complete, objective and thorough investigation of this incident." — St. Louis Circuit Attorney Kim Gardner

In a tweet, Gardner also asked that the media and the public "refrain from speculation and drawing conclusions" about the case until the facts are gathered.

The two on-duty officers rushed Alix to a hospital while phoning in the incident to dispatch, the St. Louis Post-Dispatch reported.

Alix was pronounced dead at St. Louis University Hospital, St. Louis' Fox 2 reported. It was not immediately clear which of the two on-duty officers had fired the weapon or why they were at the home when policy requires them to patrol their assigned district.

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Hayden said both of the on-duty officers have been with the department for nearly two years. He said Alix was with the department for more than two years and served time in the military. Alix is survived by her husband, mother, father, and sister.

A police source told the Post-Dispatch that Alix and the two on-duty officers were close and often worked together. Neither of the two on-duty officers was injured, but the officer responsible for the shooting was hospitalized Thursday morning after delivering Alix to the hospital, though it was unclear why, according to the police source. The officer's hospitalization was not confirmed by the department.

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The St. Louis Police Department’s Force Investigation Unit is also assisting in the case.