The name of the victim had not been released and no suspect had been arrested, the Los Angeles Times reported.
The shooting occurred shortly before 1 p.m. at the San Jose funeral of Jeffrey Pettigrew, 51, president of the San Jose chapter of the Hells Angels, that was attended by about 4,000 people, the newspaper said. Pettigrew was killed at a casino in Nevada last month, police said.
The Times said Pettigrew was allegedly shot by a member of the Vagos, a rival motorcycle gang. Ten Vagos members were arrested this month drug trafficking and other charges.