The social media giant Meta announced on Wednesday removing 63,000 accounts connected to the Nigerian cybercrime scene that were attempting to target users in the United States in financial sextortion scams.

The accounts were being operated by the Yahoo Boys, a term used to refer to  rather than a traditional hierarchical criminal conspiracy.

“While our investigation showed that the majority of these scammers’ attempts were unsuccessful and mostly targeted adults, we did see some attempts to target minors,” said Antigone Davis, Meta’s global head of safety, adding that these were referred to NCMEC.

The social media company’s crackdown follows the FBI warning earlier this year of the “growing threat” that financially motivated extortionists pose to children. These criminals coerce typically teenage males into sharing sexually explicit images before threatening to publicly release those images unless the victim pays an extortion fee, often in “gift cards, mobile payment services, wire transfers, or cryptocurrency.”

Meta said that within the 63,000 accounts that attempted to directly engage in financial sextortion scams it also uncovered “a smaller coordinated network of around 2,500 accounts that we were able to link to a group of around 20 individuals” based in Nigeria.

These individuals were mostly targeting adult men in the United States, using fake accounts to mask their identities. They were also linked to thousands of other assets, including accounts, pages and groups, that provided tips for conducting scams — including scripts that were for sale, guides to use when scamming people, and links of photographs to use when creating a fake account.

Last year the Click Here podcast interviewed a former Yahoo Boy about his experiences scamming people online. Although the individual engaged in regular romance scams rather than sextortion, they revealed several facets of the large cottage industry driving fraud in Nigeria.

Meta said it had designated the Yahoo Boys as a banned entity under its Dangerous Organizations and Individuals policy, which the company described as “one of our strictest policies — which means we remove Yahoo Boys’ accounts engaged in this criminal activity whenever we become aware of them.”

The company said the majority of the Yahoo Boys accounts had been detected and disabled by its automated enforcement systems, but its expert human investigators were needed to spot the remaining accounts and understand how the cybercriminals were evading automated detection.

Meta said it has used “the new tactics we observed to further improve our ability to detect accounts, Groups and Pages engaging in this activity.”

“Since these criminals don’t limit themselves to any one platform, we also share relevant information with other tech companies through the Tech Coalition’s Lantern program, so they can take action too,” the company added.

U.S. prosecutors continue to pursue cybercrime cases against Nigerian nationals. On Wednesday the Department of Justice announced a nearly 13-year prison sentence for Bamidele Omotosho, a 42-year-old man who was part of multiple hacks and financial scams.