CHICAGO (AP) — The family of a 34-year-old killed by a suburban Chicago police officer in March as she exited her burning car with a knife is suing, saying the officer opened fire when non-lethal devices were at the ready.

Lawyers for DeCynthia Clements' family filed the lawsuit Wednesday in Chicago federal court against the city of Elgin, Lt. Christian Jensen and other Elgin police.

It says officers learned Clements suffered from mental illness during an hour-long standoff along Interstate 90 but that Jensen shot her three times as she took a single step from the car.

Family lawyer Andrew Stroth said the incident raised questions about "racial profiling." Another family attorney, Antonio Romanucci, said it demonstrated "blatant and unnecessary use of deadly force."

Elgin officials didn't immediately return messages seeking comment.