(CNN) -- Hundreds of Asian-American business owners have been threatened with death if they don't send money to extortionists phoning from China.
Some terrified business owners have wired thousands of dollars to the extortionists, CNN affiliate KGO reported.
Authorities said the callers are demanding $20,000 to $30,000 to get a brother out of jail in China. The business owners are threatened with death, harm to their children or bombing of their business, police told KGO.
The threats have plagued business people in Atlanta, Georgia; Boston, Massachusetts; Chicago, Illinois; Dallas and Houston, Texas; Los Angeles and San Francisco, California; as well as in New Jersey, New York and Toronto, Canada, police said.
The calls have been made from an Internet calling service called Skype, which lets users make free calls using computers.
The phone bandits may have received as much as $100,000 from across the United States, Detective Jameson Pon of the San Francisco, California, police told KGO.
The transfers are hard to trace, because the extortionists are likely using fake identification cards to set up accounts with money wire services.
"We don't know which Western Union branch in China is being used. If you have the manpower for fixed surveillance in China, you could likely catch the culprit," Pon said.
The extortionists might be a gang of four or five people, according to police in California and New York.
In New York City, there have been approximately 75 reported victims, according to police. No one from New York reported having sent money to the extortionists. About 50 victims reported calls in San Francisco.
No one has been physically harmed, police said.