Cryptocurrency exchange Binance temporarily stopped its blockchain network after hackers fled with around $570 million worth of its BNB token.

Binance explained late Thursday a cross-chain bridge linking with its BNB Chain was targeted, enabling hackers to move BNB tokens off the network. Cross-chain bridges are a technology that allows the transfer of tokens from one blockchain to another.

The crypto behemoth said it had worked with transaction validators to halt the creation of new blocks on BSC, suspending all transaction processing while a team of developers investigates the breach.

Binance is the world’s largest crypto exchange by trading volume.

“An exploit on a cross-chain bridge, BSC Token Hub, resulted in extra BNB. We have asked all validators to temporarily suspend BSC,” Changpeng Zhao, Binance’s CEO, said in a tweet Thursday evening.

“The issue is contained now. Your funds are safe. We apologize for the inconvenience and will provide further updates accordingly.”

BNB Chain has since resumed operations.

In total, hackers were able to drain 2 million BNB tokens — about $570 million at current prices — from the network, Binance’s BNB Chain said in a blog post on Friday.

The exploit was enabled “through a sophisticated forging of the low level proof into one common library,” BNB Chain said.

An earlier estimate from the firm placed the total amount withdrawn in a range of $100 million to $110 million.

Binance said it managed to freeze $7 million of funds with the help of its security partners..

The value of BNB plummeted more than 3% Friday morning to $285.36 a coin, according to CoinMarketCap data.

BNB Chain, originally known as Binance Chain, was first developed by Binance in 2019. Like other blockchains, it features a native token, called BNB, that can be traded or used in games and other applications.

The hack isn’t the only one, a total of around $1.4 billion has been lost to breaches on cross-chain bridges since the start of 2022, according to data from blockchain analytics firm Chainalysis.