An autopsy report shows a young black man shot dead by San Francisco police suffered 20 gunshot wounds, including six in the back, and had drugs in his system when he died in the shooting that sparked protests and calls for the chief's removal.

The San Francisco coroner's report released Thursday showed that Mario Woods, 26, also had two gunshot wounds in his buttocks and others to his head, legs, abdomen and hands. Some of the wounds could have been from the same bullet, the autopsy says.

It also shows that Woods had used methamphetamine, marijuana, antidepressants and cough medicine before he was shot.

Investigators have said five officers opened fire on the knife-wielding Woods on Dec. 2 and that 27 shell casings were recovered at the scene where Woods died.

Police had encountered him while searching for an assailant who stabbed a stranger earlier in the day.

Police say Woods ignored commands to drop the knife and resisted even after he was shot several times by a "bean-bag" gun and pepper-sprayed.

The shooting was captured on video and circulated widely online, igniting ongoing protests over police tactics.

The department, district attorney and police commission have each launched an investigation.

"It is difficult for anyone to watch videos of the shooting. Similarly, it is equally as difficult to read the medical examiner's report," the San Francisco Police Department said in a prepared statement.

It said the agency is "committed to a thorough review of the shooting, and this report will be an important component of all three ongoing independent investigations."

Chief Greg Suhr says he won't resign as a result of the shooting and Mayor Ed Lee says he won't fire him.

Suhr and the mayor called on the U.S. Department of Justice to review department policy and procedures and advise the city on reforms. The DOJ said last week it would conduct the review.

Woods family has filed a legal claim against the police and the city, arguing that officers didn't have to open fire.

The family's attorney John Burris told the San Francisco Chronicle that the autopsy report bolsters the legal claim and that "the officers should have taken the time when they saw he was not responding, and not created a confrontation with him."