Authorities in Vietnam busted a sports betting ring reportedly worth more than $300 million in the northern part of the country, local media reported.

According to Thanh Nien News, the underground betting ring—which mainly dealt in football—had a total bet value of VND7.6 trillion ($340 million). Investigators said Bui Khac Hien, who lived in Hanoi’s Thanh Xuan District, operated the website, whose servers were hosted overseas.

Players, mostly from northern and central cities in Vietnam, used fake names and addresses to avoid detection, police said.

The 52-year-old man was arrested over the weekend, the report added. So far, authorities have arrested some 23 people connected with the sports betting ring since June 9. Many of those arrested acted as debt collectors, investigators said.