(CNN) The family of Stephon Clark, an unarmed black man who was shot and killed in his grandmother's backyard by Sacramento police last year, has filed a wrongful death lawsuit against the officers involved and the city of Sacramento.

The federal lawsuit, filed Monday, alleges the 22-year-old was racially profiled, and the officers used excessive force in the shooting incident. The two officers failed to identify themselves or issue a verbal warning before firing approximately 20 shots, the suit said. The lawsuit also alleges the officers did not get him medical attention immediately after the shooting.

The Sacramento Police Department has never publicly identified the officers.

Clark was struck seven times , including three times in the back, according to an autopsy released by the Sacramento County Coroner's office. An independent autopsy found that Clark was shot eight times, six of those wounds in his back, according a forensic pathologist retained by Clark's family.

Authorities have said the two Sacramento officers who shot Clark were responding to a report that a man had broken car windows and was hiding in a backyard. Police chased that man -- later identified as Clark -- who hopped a fence into his grandmother's property. He was shot in her backyard on the night of March 18.

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