CHICAGO (CBS) — An Elgin police officer shot and killed a 34-year-old woman armed with a knife early Monday, after she allegedly fled a traffic stop, and then her SUV caught fire during a standoff on the Jane Addams Tollway.

Elgin police said, around 12:30 a.m., officers spotted a suspicious vehicle on Cedar Avenue in Elgin, and the driver fled the scene. Officers gave chase, but soon halted their pursuit of the SUV. A short time later, the vehicle was spotted headed west on I-90 near Route 25.

“It had obvious signs of damage,” Elgin Police Chief Jeff Swoboda said. However, he said it was unclear if the vehicle had been damaged before it got on the expressway, or if it recently had been in a crash.

decynthia clements Elgin Police Fatally Shoot Woman Armed With Knife After SUV Catches Fire On Jane Addams Tollway

Decynthia Clements (Photo supplied to CBS)

Officers contacted the driver, 34-year-old Decynthia Clements, but disengaged when they noticed the woman was armed with a knife, and began negotiating with her to try to get her to surrender peacefully, according to police.

“During that time, she would periodically move her car up several feet,” Swoboda said.

After negotiating with the woman for more than an hour, officers noticed a fire had started in the vehicle.

Swoboda said officers approached the vehicle to try and pull the woman out, but said there was “an exchange” that prompted Lt. Christian Jensen to open fire on the woman.

Police did not explain exactly what happened to prompt Jensen to shoot, or what started the fire in the SUV.

“That’s the part that the state police will be investigating what occurred,” Swoboda said.

Clements was taken to St. Alexius Medical Center in nearby Hoffman Estates, where she was pronounced dead. She leaves behind a 21-year-old.

“I just want to the world to know that she was a loving, caring mom,” a Clements family member said.

“I want to express my condolences to the family. Anytime someone loses their life, especially in an incident like this, it’s just extremely sad,” Swoboda said.

Officers on the scene were wearing body cameras, so the video footage would be part of the investigation by Illinois State Police, according to Swoboda.

Jensen has been placed on administrative leave, pending the results of the investigation into the shooting.

Illinois State Police blocked traffic in both directions on the Jane Addams Tollway after the shooting to investigate, but reopened the eastbound lanes around 5 a.m. The westbound lanes were closed until about 8:30 a.m.

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