One of the most popular cross-blockchain bridges may have been the victim of a hack worth over $326 million on Wednesday.

In a tweet, the project’s official Twitter handle confirmed that the bridge is currently down while the team investigates a potential exploit, and the officialwebsitesimply reads, “Portal is Temporarily Unavailable.”

On-chain analysts called attention to an 80,000 ether (ETH)transactionfrom Wormhole to an address currently in possession of over $250 million worth of ETH. According to anotherdeveloper, the attacker also kept 40,000 ETH on Solana, where they have been selling for other assets.

In a tweet, prominent pseudonymous Paradigm security researcher “samczsun” noted that the Wormhole team has reached out to the exploiter’s address on the Ethereum network, offering a $10 million bounty for returning the funds.

The hack has raised alarm in DeFi circles because it now means ETH that has been bridged to Solana may be unbacked.

Cross-blockchain bridges often work by taking an asset, such as ETH, and locking it in a contract to issue a parallel asset on the bridged chain.

It is not immediately clear what the ramifications for Solana lending markets and other protocols might be if the ETH issued by Wormhole cannot be bridged back to the Ethereum main chain and is now valueless.