At 00:00 UTC, Bancor experienced a security breach. A wallet used to upgrade some smart contracts was compromised. This compromised wallet was then used to withdraw ETH from the BNT smart contract in the amount of 24,984 ETH (~$12.5M). The same wallet also stole 229,356,645 NPXS (~$1M) and 3,200,000 BNT (~$1oM).
Once the theft was identified, Bancor was able to freeze the stolen BNT, limiting the damage to the Bancor ecosystem from the theft. It is not possible to freeze the ETH or any other stolen tokens. Primary analysis shows this wallet address and the transaction hash that led to the breach. 22,000 ETH were transferred for a transaction cost of just $0.88 at 61 GWEI. Read the official statement here.