The hackers behind the cyberattack on Colonial Pipeline that shut down a major oil network over the weekend said they didn’t intend to cause such a disaster and were merely trying to make some money by selling their virus software.

The FBI confirmed on Monday that DarkSide ransomware was responsible for the Colonial Pipeline attack. Darkside is a group of organized hackers selling software hacking tools to other criminals to carry out attacks on wealthy organizations and entities, according to the cybersecurity firm Cybereason.