The crypto exchange is offering a $20 million reward for information leading to the hackers’ arrest. Coinbase terminated customer support agents who leaked customer data.

Coinbase on Thursday said criminals bribed and duped their way to stealing cryptocurrency from its users, then tried to blackmail the exchange to keep the crime quiet.

Coinbase Global said Thursday that it has refused to pay a $20 million ransom demand from cybercriminals who bribed the company’s overseas customer support agents to steal sensitive user data.The cryptocurrency exchange estimated that the incident could cost from $180 million to $400 million,

Coinbase, the largest cryptocurrency exchange based in the U.S., said Thursday that criminals had improperly obtained personal data on the exchange’s customers for use in crypto-stealing scams and were demanding a $20 million payment not to publicly release the info.

Instead of paying the $20 million ransom, Coinbase offered the same amount of money for information leading to the attackers.

The inquiry continued even after the commission dropped a lawsuit accusing Coinbase of illegally marketing digital currencies to the public.

Coinbase Global Inc. is cooperating with the US Securities and Exchange Commission on an agency probe into its previously reported user metrics, the company said Thursday.

Coinbase said on Thursday it strongly believes a regulatory investigation by the U.S. securities regulator into its disclosures of monthly transacting users should not continue.