By Dan Whitcomb

LOS ANGELES (Reuters) - An unarmed 25-year-old black man slain by Los Angeles police officers in August suffered three gunshot wounds, including one to his back, a long-awaited autopsy report showed on Monday.

Police have said two officers shot and killed Ezell Ford, described by a family lawyer as mentally challenged, after he struggled with one of them and tried to grab the officer's gun during an Aug. 11 scuffle in a poor neighborhood of Los Angeles.

Ford's death, which came just days after the fatal shooting of 18-year-old Michael Brown by a white police officer in Ferguson, Missouri, touched off demonstrations outside police headquarters in Los Angeles.

More protests were planned for Monday afternoon following release of the report.

The autopsy conducted by medical examiners for the Los Angeles County Coroner's Office showed that Ford suffered gunshot wounds to the arm, back and right flank. The wounds to his back and flank were fatal, it said.

Toxicology tests showed Ford had marijuana in his system at the time of his death.

The autopsy report has been completed for some time but police asked that it be kept under wraps during an investigation into the shooting. Mayor Eric Garcetti asked that it be released by the end of this year.

Los Angeles Police Chief Charlie Beck scheduled a news conference for Monday afternoon to discuss the autopsy report.

Police officials say no officer was hurt in the incident. The Los Angeles Times has reported that the officers involved in the scuffle with Ford were Asian-American and Latino.

Ford's family filed a federal lawsuit in September, seeking damages of $75 million for what they called the officers' violation of his civil rights.

(Reporting by Dan Whitcomb; Editing by Steve Gorman, David Gregorio and Peter Cooney)