The Ronin Network, a blockchain system that runs Sky Mavis' popular NFT game Axie Infinity, has been hacked, with about $625 million worth of funds stolen in a massive theft.

The Ronin bridge was "exploited" for 173,600 Ethereum and 25.5M USDC, the Ronin Network announced in a blog post, adding that the bridge and the Katana Dex have now been halted as a result. The Ronin Network said it's actively working with law enforcement, as well as forensic cryptographers and its own investors to ensure that "all funds and recovered or reimbursed."

In the announcement, the Ronin Network said it discovered today (March 29) that the validator nodes on the Ronin validator for Sky Mavis and the Axie DAO nodes were compromised on March 23, leading to the theft. Two transactions took place, with the hacker using "private keys" to create fake withdrawals, the company said. "We discovered the attack this morning after a report from a user being unable to withdraw 5k ETH from the bridge," Ronin Network said.