Seventeen members of a Russian hacking group dubbed “Evil Corp.”—described as “one of the world’s most prolific cybercriminal organizations”—were charged Thursday with stealing at least $100 million from hundreds of banks around the world, according to a joint press release from the U.S. Justice and Treasury departments. U.S. authorities said the Moscow-based group may have had proceeds “significantly higher” than the $100 million taken since 2016 from more than 300 financial institutions, mainly in America and Britain. The attacks are reported to have infiltrated computers in more than 40 countries.

The charges were accompanied by U.S. sanctions imposed by Treasury on all 17 of the accused, as well as seven entities that include Evil Corp. Radio Free Europe reports a $5 million reward was put up for the arrest of alleged ringleader Maksim Yakubets, a Russian national with alleged ties to the FSB intelligence service and who Treasury officials said “provides direct assistance to the Russian government’s malicious cyber efforts, highlighting the Russian government’s enlistment of cybercriminals for its own malicious purposes.” Assistant Attorney General Brian Benczkowski called the attacks among “the worst computer hacking and bank-fraud schemes of the past decade,” adding that Yakubets was responsible for conducting “the kinds of criminal schemes so audacious and sophisticated they would be difficult to imagine if they were not real.”