Chinese authorities have arrested six suspects behind a World Cup gambling ring that was hosting more than 10 billion yuan — or $1.5 billion USD — worth of cryptocurrency bets, according to a statement released yesterday by the police department in Guangdong province.

The gambling syndicate ran on the dark web, accepting bets in the form of bitcoin, ethereum, and litecoin for an eight-month stretch before being apprehended. It attracted more than 300,000 players from different countries, and 8,000 “agents” who earned commissions for recruiting new members through a pyramid scheme-like system, according to the South China Morning Post.

World Cup gambling is big worldwide — but China’s been cracking down on it. Most forms of gambling are illegal across almost the entire country, outside of two officially sanctioned lotteries.

The bust that took down the dark web syndicate was a part of China’s larger plans to stem the criminal activity — though this was the first to involve cryptocurrency, according to Guangdong law enforcement. Thus far, they’ve arrested 540 suspects and frozen more than 260 million yuan as a part of their efforts.