The man was gunned down at Oak Hill Cemetery around 1 p.m. during the funeral for Jeffrey "Jethro" Pettigrew, president of the Hells Angels' San Jose chapter who was fatally shot last month, police spokesman Jose Garcia.
The shooting victim died later Saturday at a hospital, Garcia said.
Police would not release his name or say what chapter of the group he belonged to, but they had verified the man was a member of the Hells Angels, Garcia said.
No one else was injured.
Police were interviewing witnesses, but had no early leads.
"No one has been identified as a suspect, no one has been arrested," Garcia said.
A member of the rival Vagos motorcycle club is accused of killing Pettigrew on Sept. 23 in a Sparks, Nev., casino shooting that sent gamblers diving for cover. The mayor canceled a regional motorcycle rally as a result.
Saturday's shots were fired as thousands gathered for Pettigrew's funeral despite a heavy police presence.
Video from television stations showed dozens of police at the cemetery after the shooting, with sections blocked off with police tape.
One witness to the shooting, Valerie Hoffman, told television station NBC11 she was shocked.
"I've known Hells Angels and all the other groups for years and years and years, and there is a code of ethics," she said. "You never do anything at a funeral. I mean that is just completely abominable."
Garcia said the scene of the shooting "appeared to have been tampered with." He did not elaborate. Police did not say how many shots were fired.
No one else at the funeral was hurt.
Police and Santa Clara County sheriff's deputies were sent to guard the Hells Angels headquarters in San Jose, the San Jose Mercury News reported.