The cryptocurrency mining marketplace NiceHash has been hacked, its team said Wednesday.

Posting on social media, NiceHash said that “there has been a security breach involving NiceHash website” resulting in a loss of funds. NiceHash, formed in 2014, serves as a marketplace for miners to rent out their hash rate to others.

The announcement follows an hours-long outage and reports from a multitude of users that their NiceHash-associated wallets had been emptied. NiceHash previously announced that it was “under maintenance,” a message that it had posted to its official website as well.

The company said in its statement:

“Importantly, our payment system was compromised and the contents of the NiceHash Bitcoin wallet have been stolen. We are working to verify the precise number of BTC taken. Clearly, this is a matter of deep concern and we are working hard to rectify the matter in the coming days. In addition to undertaking our own investigation, the incident has been reported to the relevant authorities and law enforcement and we are co-operating with them as a matter of urgency.”

Though the team didn’t disclose an exact amount, a wallet address circulated by NiceHash users suggest that as many as 4,736.42 BTC – an amount worth more than $62 million at current prices – has been stolen.

The NiceHash team urged users to change their non-NiceHash online passwords as a result of the breach and subsequent theft.

“While the full scope of what happened is not yet known, we recommend, as a precaution, that you change your online passwords,” they wrote in the statement.

NiceHash did not immediately respond to an emailed request for comment.

CoinDesk will continue monitoring this developing story.

Image via Shutterstock

This article has been updated for clarity.