NICOSIA — Cyprus police have seized servers that were used to sell social security numbers and other personal information stolen from 24 million U.S. citizens, a law enforcement official said Thursday.

Police Cybercrime Department Chief Andreas Anastasiades told the state-run Cyprus News Agency that four websites were taken down in a joint operation with the U.S. Federal Bureau of Investigation and the Internal Revenue Service.

Anastasiades said the servers’ manager, who is a resident of Cyprus, cooperated with authorities following a six month-long investigation.

A U.S. Department of Justice statement said the SSNDOB Marketplace websites operated for years and generated more than $19 million in sales revenue.

The personal information that was hacked included the names, dates of birth and social security numbers of U.S. citizens.

According to the statement, SSNDOB administrators advertised on darkweb criminal forums. To avoid detection, administrators used online monikers to conceal their true identities, maintained servers in various countries and required buyers to use digital payment methods like bitcoin.

It said that the international operation “to dismantle and seize this infrastructure” resulted from cooperation with law enforcement authorities in both Cyprus and Latvia.