A 32-year-old man suffered a skull fracture Saturday night when six men attacked and robbed him in San Francisco’s North Beach neighborhood, authorities said.

San Francisco police responded to a robbery reported at 10:36 p.m. near the intersection of Beach and Columbus streets, which is located just a couple blocks from Fisherman’s Wharf. The group approached the victim from behind and knocked him unconscious before taking his backpack and cell phone, police said.

The victim, identified by his friends as Vinh Vu, was taken to a hospital with life-threatening injuries.

According to a GoFundMe online fundraiser for his medical expenses, Vu was walking to his second job in Fisherman’s Wharf that night when the men attacked.

As of 4:30 p.m. Tuesday, the fundraiser received more than $10,000.

Police have not arrested any of the suspects in the case.

Gwendolyn Wu is a San Francisco Chronicle staff writer. Email: gwendolyn.wu@sfchronicle.com Twitter: @gwendolynawu