Bankrupt crypto currency exchange FTX is investigating “unauthorized transactions” and has moved all funds into offline storage. 

More than $400 million in crypto funds appear to have disappeared on Friday after FTX filed for bankruptcy, according to the crypto analytics firm Elliptic.

FTX did not immediately respond to a request for comment.

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FTX general counsel Ryne Miller tweeted on Saturday that the exchange had “initiated precautionary steps to move all digital assets to cold storage.” Cold storage refers to crypto wallets that are not connected to the internet to guard against hackers. 

Miller said that the firm is “investigating abnormalities with wallet movements,” but that the facts remain “unclear” and that FTX will “share more info as soon as we have it.”

FTX appeared to have verified rumors of a potential hack on the exchange’s Telegram channel and has asked customers to stay off the firm’s website and delete FTX apps, CoinDesk reported.

The Washington Post could not confirm the details of message in the firm’s private Telegram channel.

Roughly $473 million in crypto assets appear to be stolen from FTX without permission, according to Elliptic. The tokens were quickly converted to ether, the second-largest cryptocurrency, a popular technique used by hackers to prevent their funds from being seized.

“They certainly moved, we don’t know whether that was with permission or not — that’s not something we can determine from the blockchain alone,” said Tom Robinson, co-founder of Elliptic in an email.

Sam Bankman-Fried, the co-founder and chief executive of FTX, resigned on Friday just three years after the exchange he founded had gone from being an industry giant valued at $32 billion to facing collapse.