Yesterday, hackers stole $64 million from NiceHash, a company that lets users apply their extra GPUs to mining cryptocurrencies. The attack caused NiceHash to shut down its website for 24 hours, as the site’s payment system was compromised and its bitcoin wallets emptied. Today, CEO Marko Kobal and co-founder Sasa Coh appeared on a Facebook livestream to address user concerns.

“I see various kinds of emojis down there,” Kobal said at the start of the livestream, as users made their complaints heard. Numerous viewers said Kobal and Coh looked guilty, and some voiced suspicion of an inside job. The Slovenia-based company, founded in 2014, has paid out over a billion dollars to miners over the last three years, according to its founders.

That success, Kobal said, was what drew the wrong kind of attention to NiceHash. “Unfortunately, we became a target and someone really wanted to bring us down,” he said in the six minute livestream.

Law enforcement and cybersecurity experts are working with NiceHash to pinpoint the total amount of cryptocurrency stolen and how exactly the system was compromised. Kobal said that about 4,700 bitcoins were stolen on December 6th and that a hacker or a group of hackers with an IP address outside of Europe accessed NiceHash computers. Through that access, the hacker(s) obtained a NiceHash engineer’s credentials and used them to access the payment system.

The hack comes during a particularly volatile moment: today, bitcoin prices momentarily soared past $19,000 on some exchanges, after weeks of unprecedented growth.

“It was a highly sophisticated attack,” said Kobal, who said that he could share more in the coming days. Many livestream viewers asked in comments whether the company would restore their wallets. Kobal and Coh declined to comment.