A 34-year-old woman was fatally shot by police early Monday in northwest suburban Elgin.

About 12:34 a.m., officers made contact with a “suspicious vehicle” the woman was driving near Cedar Avenue, according to Elgin police Chief Jeffrey Swoboda. She then drove off.

After initially trying to pull over the vehicle over, officers called off their pursuit, Swoboda said. A short time later, the vehicle was seen driving west on Interstate 90 near Illinois Route 25 with “obvious damage.”

Officers then made contact with the driver, Decynthia S. Clements, who was armed with a knife, authorities said. After disengaging from the vehicle, officers negotiated with Clements for over an hour. During that time, she periodically moved her vehicle several feet.

At some point, officers noticed that a fire had started inside the Clements’s vehicle, at which point they pulled her out, Swoboda said.

“At that time an exchange occurred, and that exchange is what’s under investigation right now,” Swoboda said during a Monday press conference.

An officer ultimately opened fire and Clements was struck, Swoboda said.

She was taken to St. Alexius Medical Center in Hoffman Estates, where she was pronounced dead, Swoboda and the Cook County Medical Examiner’s Office said. She lived in Elgin.

An autopsy Tuesday found Clements died of multiple gunshot wounds and her death was ruled a homicide, the medical examiner’s office said.

“I want to offer my condolences on behalf of the Elgin Police Department to the family,” Swoboda said. “This is obviously a very sad day and we recognize that.”

The officer was identified as a lieutenant who has been with the Elgin Police Department for 19 years, according to police.

Illinois State Police are investigating the officer’s use of force.