Hundreds of protesters rallied in San Francisco on Thursday night in response to the videotaped police killing of a black man who authorities said was a suspect in a stabbing before being shot dead by several officers, local media said.

Mario Woods, 26, was shot on Wednesday afternoon amid heightened scrutiny of police violence following high-profile killings of unarmed black people across the United States since mid-2014 and a renewed civil rights movement under the name Black Lives Matter.

Demonstrators, including Woods' mother, gathered in the city's Bayview neighborhood on Thursday night chanting phrases like "No justice, no peace. No racist police," the San Francisco Chronicle and other local media reported on Friday.

San Francisco police said officers encountered Woods while investigating reports that someone matching his description had stabbed someone in the shoulder.

Police said they first tried using pepper spray and fired bean bag rounds at Woods, who they said was holding a knife and refused commands to drop it, then shot him dead when he moved toward an officer.

Video of the shooting, apparently recorded on bystanders' cell phones and uploaded to social media, showed one of about a dozen officers move directly in front of Woods as he attempted to walk away. Woods was then dropped by a hail of gunfire.

In several seconds of footage recorded from two vantage points, the phalanx of officers can be seen with their weapons pointed at Woods, whose back is to the wall of a building. It is not clear from the video if Woods was armed when he was shot.

Police said the suspect was a danger to others and that "the officers could not allow him room to harm anyone else."

Critics, including San Francisco Public Defender Jeff Adachi, have suggested the shooting may have been unnecessary.

"Based on what we see in this video, it does not look like the officers who fired the fatal shots were in immediate danger of being killed and that there were other alternatives that could have been taken," Adachi told the San Francisco Chronicle.

Thursday night's demonstration had largely dispersed by about 9 p.m. local time, according to the reports, and there was no word of arrests of clashes with police.