Man pummeled in SF brass-knuckles beating

A witness captured a picture of an assailant who allegedly used brass knuclkes to beat a man on the sidewalk along Mission Street in San Francisco. The suspect is seen in the background walking north on Mission with an unidentified woman behind him. less A witness captured a picture of an assailant who allegedly used brass knuclkes to beat a man on the sidewalk along Mission Street in San Francisco. The suspect is seen in the background walking north on Mission ... more Image 1 of / 3 Caption Close Man pummeled in SF brass-knuckles beating 1 / 3 Back to Gallery

Police in San Francisco are on the hunt for a assailant with brass knuckles who cold-cocked a 36-year-old man on a sidewalk Sunday in the city’s Mission Bernal neighborhood.

The attacker, described as a man in his 20s, walked up to the victim around 4:25 p.m. on the sidewalk on the 3200 block of Mission Street near the Knockout bar, police and a witness said.

Armed with a fist-full of brass knuckles, the assailant began wailing on the victim, leaving him pummeled and unconscious at the scene.

A witness who saw the brutal beating said the attacker hit the victim three-to-five times before passersby intervened and called 911.

The witness, who asked not to be named for safety reasons, said the attacker took off northbound on Mission Street toward Valencia Street with an unidentified woman walking behind him.

Bystanders ran to help the victim, who was unconscious with a bleeding head wound. The man regained consciousness about 10 minutes later as police and paramedics arrived at the scene.

No suspect was identified in the assault.

The victim, meanwhile, was recovering at a hospital. Police did not release a motive for the assault.

Evan Sernoffsky is a San Francisco Chronicle staff writer. Email: esernoffsky@sfchronicle.com Twitter: @EvanSernoffsky