Authorities in China have recently shut down a bitcoin mining operation that reportedly stole over 20 million yuan – about $3 million – worth of electricity to mine the flagship cryptocurrency.

According to the South China Morning Post (SCMP) the operation saw police in Zhenjiang, Jiangsu province seize nearly 4,000 bitcoin mining machines and take “compulsory measures” against more than 20 individuals seemingly involved in the operation.

Chinese police found the operation after being alerted by a local power company that found the abnormal electricity usage odd and tipped them off. In a statement, Zhenjiang’s police wrote:

In value, it is the largest case in the amount of electricity stolen that Jiangsu has cracked, and a rare sight in the whole country.

The Chinese government, as many crypto enthusiasts know, has taken a not-so-friendly approach to the cryptocurrency space. In 2017, it cracked down on cryptocurrency trading and initial coin offerings (ICOs), which led to the shutdown of various popular cryptocurrency exchanges at the time.

Earlier this year Reuters reported China’s National Development and Reform Commission (NDRC) announced it was “seeking public opinions” for a report in which it claimed cryptocurrency mining “should be phased out” as it doesn’t adhere to relevant laws and regulations and is “unsafe.”

It’s worth noting that back in May a prominent lawyer in China argued that both owning and occasionally trading bitcoin is legal in the country. Sina Finance, one of China’s largest news providers, has also recently added cryptocurrency support to its app.