Crypto trading venue Orion Protocol was set to pause operations Thursday after an apparent attacker drained millions of dollars worth of cryptocurrency, according to cybersecurity firm Peckshield.

Orion was the victim of a reentrancy attack in which an attacker repeatedly withdraws funds from a smart contract, PeckShield said in a Twitter message. Gal Sagie, CEO of cybersecurity company Hypernative, said the attacker deployed a fake token called ATK which was used to manipulate the Orion pools. It utilized a self-destructing smart contract.

“The protocol is being paused as we speak,” Peckshield said in a Twitter message. The firm said it is assisting Orion. "The root cause is now confirmed w/ the team and they are fixing the bug now."

Initial estimates from on-chain sleuths placed the losses at $2.8 million on Orion’s Ethereum implementation and $200,000 on its BSC implementation. A wallet identified as the attacker’s began passing ether tokens through privacy mixer Tornado Cash shortly after the event.

Orion Protocol CEO, Alexey Koloskov, told investors that "all funds are safe and secure," in a tweet thread in the hours following the attack.

"We have reasons to believe that the issue was not a result of any shortcomings in our core protocol code, but rather might have been caused by a vulnerability in mixing third-party libraries in one of the smart contracts used by our experimental and private brokers," he said.

The price of Orion’s native token ORN is little changed following the apparent attack, up nearly 14% in the last 24 hours to $1.03.

UPDATE (Feb. 3, 08:34 UTC): Adds statement from Orion Protocol CEO starting in third paragraph.