Millbrae police said Thursday that businesses have recently been receiving calls from someone speaking in the Mandarin Chinese dialect, demanding $25,000 to $35,000 and threatening physical harm and damage to the business.
Victims also noted the caller had a Taiwanese accent, according to police.
Authorities have reported similar crimes in recent weeks in San Francisco, San Jose, Fremont, Sunnyvale and Milpitas.
San Francisco police and the FBI said earlier this month that gang task force investigators had been assigned to the case.
Millbrae police said the crimes had previously been reported in the Los Angeles area as well.
Businesses that receive such threats are advised to note as much information as possible about the caller and call 911 immediately.