(Evan Cobb/AP)

Three men in India were arrested this week after police uncovered a huge scheme that targeted more than 11,000 people in the United States.

Men posing as officials from the U.S. Internal Revenue Service left thousands of voice messages claiming to have found irregularities in the victims’ tax records. The messages instructed them to call back or face legal action. But the phone number they gave connected unsuspecting people in the United States to Indian con men sitting in a second-floor office in an upscale area called Koregaon Park in the western city of Pune.

India’s call-center industry has contributed to the rapid development of sleepy cities such as Pune in the past three decades, drawing hundreds of thousands of ambitious job seekers to call centers for multinational firms. But in recent years, Indian con artists have used English accents and Americanized names, which are common in call centers, for a different reason: to cheat foreigners.

Indian police officers have sent thousands of emails to victims in the United States asking for details about how they were scammed. Only three people have replied, said Assistant Police Inspector Sagar Panmand from Pune’s cybercrime branch, which raided the call center.

Indian investigators said they didn’t know how many people in the United States were affected by the scheme or how much money the scammers took. They also said it was unclear how the computer-savvy con men got the victims to transfer money to India but said it probably involved the use of gift cards from Target, iTunes and Walmart.

Panmand said early investigations suggested that there were at least two similar call centers in Delhi and the state of Rajasthan that police were trying to trace.

Authorities learned about the Koregaon Park call center after they discovered another ring of scammers in January that had targeted users of Apple products in the United States. At least 1,500 people in the United States received pop-up notifications on their iPhones, iPads or Macs saying that their systems had crashed. The pop-up messages also gave a phone number of an Apple service center — which really was a fake call center in India. The scammers then asked their targets to pay for the service of “fixing” their systems by buying iTunes credit, that could be transferred to the con men and cashed in.

During the raid Monday night, police seized hard drives and laptops with the personal details of 11,000 people in the United States. “They had bank details, bank account numbers, phone numbers, addresses, everything,” Panmand said. “American authorities will need to do their own investigations to find out how all this data got out.”

He said Pune police were in contact with the Federal Trade Commission and would support U.S. authorities in their investigations. The FTC did not immediately respond to a request for comment.