Protesters march after the funeral of police shooting victim Stephon Clark in Sacramento. Picture: Reuters/Bob Strong

Sacramento - Stephon Clark, the unarmed 22-year-old killed by Sacramento police officers earlier this month, was shot eight times, with most of the bullets hitting him in the back, according to an independent autopsy requested by his family's attorneys.

Bullets struck Clark in the neck, back and thigh, breaking bones and piercing his lung, said Bennet Omalu, a forensic pathologist. The bullets combined to make Clark "bleed massively," Omalu said.

"His death wasn't instantaneous," Omalu, who is best known for his role in highlighting concussive damage to football players, said at a news conference Friday. Instead, Omalu said, "Death took about three to 10 minutes."

Read more: 'Armed' man shot 20 times by cops was holding an iPhone

Omalu announced his findings amid continuing public anger over Clark's death. A day earlier, hundreds of mourners gathered to grieve for Clark at an emotional funeral that alluded to the tensions lingering in the community.

Clark, a black man and a father of two, was fatally shot on March 18 by Sacramento police officers. Police in the California capital said they were responding that night to a call about someone breaking into vehicles.

The shooting was captured on footage recorded by body cameras and a helicopter video. This footage showed Clark running to the backyard of his grandmother's house, where officers fired 20 times at him. Officials have not said how many times they believe Clark was struck.

The officers said they fired thinking Clark had a gun, but police have since said he was holding only an iPhone.

Omalu said that Clark "was not facing the officers" when he was killed. Benjamin Crump, an attorney for Clark's family who spoke before Omalu on Friday, said the autopsy findings contradicted the police narrative of Clark's death.

The Sacramento police declined to comment on Omalu's findings and Crump's statement, saying it "would be inappropriate" to do so before the release of the county coroner's report and the conclusion of the ongoing investigations into the shooting.

Also read: US police release videos of fatal shooting of unarmed black man

"We acknowledge the importance of this case to all in our community and we are committed to a thorough and comprehensive investigation," the Sacramento police said in a statement.

The Sacramento police said the department had not been given the county coroner's official report. The county coroner's office did not respond to messages seeking details on Clark's autopsy or its findings earlier Friday. County records showed only the date of Clark's death and described him as a 22-year-old black man.

According to Omalu, six of the eight shots that hit Clark struck him in the back, while a seventh bullet hit him "slightly to the side of his body, but to the back of the side."

"You could reasonably conclude that he received seven gunshot wounds from his back," said Omalu, who conducted his autopsy on Tuesday and finished his report Wednesday. Omalu said all seven of these bullets could have been fatal on their own.

An eighth bullet that struck Clark in the thigh suggested that the 22-year-old "was either on the ground or falling close to the ground" when that shot hit him, Omalu said.

Read more: Protests erupt after US police gun down unarmed black man

While he spoke, Omalu pointed to a diagram of the autopsy findings, which showed that most of the bullets struck Clark on the right side of his body, including one that appeared to hit him near his armpit.

Omalu's news conference served as a grim reminder of the devastation gunfire can wreak upon the human body. A bullet that struck Clark's right arm shattered his bone "into tiny bits," Omalu said. Another injured his spinal cord; others "perforated" his chest cavity and lungs, he said.

Clark is one of at least 269 people fatally shot by police so far this year, according to The Washington Post's database tracking such deaths. Since The Post began to track these shootings in January 2015, the Sacramento police have fatally shot six people. Including Clark, five of the six have been black men.

The release of the video footage capturing Clark's death has given way to repeated protests in Sacramento. Demonstrators have blocked fans from entering NBA games, marched on the city's streets and gathered Tuesday night at a City Council meeting to protest.

Stevonte Clark, wearing a shirt with his brother's face on it, sat at the council's dais during the meeting and chanted his brother's name.

Mayor Darrell Steinberg, in an interview the following day, said he was "extremely conscious" of the concerns many have expressed regarding police accountability in recent years.

"There is deep pain and anguish" in Sacramento, he said. "It's our job to bear some of that pain, and to help translate the anguish and grieving and the historic pain [of black communities] into tangible and real change."

Clark's relatives and civil rights leaders have called for full transparency in the investigation into his death as well as charges for the two officers involved.

Just under 1 000 people are shot and killed by police officers each year, according to The Post's database. Just a handful of those shootings each year lead to criminal charges, and convictions are even more rare, which has prompted intense criticism from civil rights activists across the country.

The Sacramento police department is conducting an investigation into Clark's death, while the Sacramento County district attorney's office is also conducting its own review.

Earlier this week, California Attorney General Xavier Becerra, D, and Sacramento Police Chief Daniel Hahn announced that the state Department of Justice would provide independent oversight of the police investigation into the shooting.

That announcement came the same day that Louisiana Attorney General Jeff Landry said his office would not pursue criminal charges against two Baton Rouge police officers who fatally shot Alton Sterling in 2016, one of many that have prompted intense protests nationwide in recent years.

Hahn said he had confidence in his department's ability to investigate the shooting but felt that, given "the extremely high emotions, anger and hurt in our city," it was best for the community and the police force alike to have the state step in.

"Our city is at a critical point right now, and I believe this will . . . help build faith and confidence in the investigation from our community," Hahn said.