“Suspicious” transactions totaling over $3 million were sent out of Bitcoin Lightning-based exchange FixedFloat in the past 24 hours, security firm CertiK told CoinDesk in an email.

CertiK said funds were moved in ether {{ETH}} and tether {{USDT}} to wallets on the Ethereum and Tron networks, respectively. CertiK described the activity as an "exploit" in the email.

“Approximately $2 million of the funds were deposited in eXch, similar behavior to the FixedFloat incident on 16 Feb, with another $100k USDT deposited to a binance wallet on Tron,” the firm said.

FixedFloat's website is down for “technical work” as of early European afternoon hours on Tuesday. Social media accounts haven’t commented on the withdrawals and FixedFloat’s last post on X is dated March 31.

FixedFloat is a fully automated service for exchanging cryptocurrencies and tokens and is based on Bitcoin Lightning, a network atop the main Bitcoin blockchain that uses micropayment channels for faster and cheaper transactions.

A support representative on FixedFloat confirmed to CoinDesk that the exchange had faced a technical error. They did not comment on the suspicious transfer activity.

“We had some minor technical problems and we switched our service to the technical work mode. The recovery time is still unknown,” the support staff said via a live chat.