A POLICE officer and mum-of-one has died after her colleague “unintentionally” shot her while on duty.

Krystal Rivera, 36, was killed during a confrontation with armed suspects in Chicago.

The tragedy unfolded when Rivera and other officers were patrolling a neighbourhood on Thursday and tried to stop a suspect, NBC Chicago reports.

The suspect fled on foot into a nearby apartment as cops ran behind, Chicago Police Department Superintendent Larry Snelling said.

When police entered the apartment, another person pointed a rifle at them.

An officer discharged his weapon during the confrontation – and Rivera was shot, Snelling said.

As she was rushed to hospital, the police vehicle caught fire and Rivera had to be put in another car, he added.

She was pronounced dead at the hospital, police said.

Another officer suffered a wrist injury, according to Fox 32 Chicago.

Dozens of police officers and firefighters paid their respects, walking in procession at 3am from the hospital to the Cook County Medical Examiners Office.

The Chicago Police Department said Rivera was a “courageous and compassionate officer who devoted her career to helping others and protecting our city”.

Snelling said Rivera was a four-year veteran and the mother of a young daughter.

He said: “She was a mom, and there’s nothing like walking into a room and having to deliver this type of message to her mother and her very young daughter and the rest of her family.”

He added: “She was a hero, and she lost her life tragically doing the job that she loved. That was one of the things that her mother said, she loved her job, and the way that she worked.”

In an Instagram post, the Chicago Fire Department posted a picture of the tragic officer, saying she “made the ultimate sacrifice in service” to the city.

According to Snelling, two people inside the apartment fled the apartment but were taken into custody soon after.

He added that “several individuals” are in custody, as three weapons were recovered from the scene.

Police and the Chicago Office of Police Accountability, which assesses incidents that involve officers firing weapons, are conducting an investigation.

Speaking about Rivera, Snelling said: “She had already processed two other guns working that day.

“She was a working police officer trying to keep the street safe. And she did great work.

“And if you talk to anyone on her team, they would tell you how great of a worker she was.

“This is the risk that our officers take every single day.”

Snelling added that “this happens way too often”, saying: “An officer, a young officer, 36-years-old and four years on the job. Who was working hard… these officers are out here driving down crime while putting their lives at risk.

“I want everyone to keep this officer’s family in your prayers and understand the risk that she took every single day when she came out to do her job.”

Police are reportedly issuing a search warrant for the apartment, and a forensic investigation is said to be underway in the apartment