The nuclear research hub Idaho National Laboratory (INL) confirmed that it fell victim to a data breach on Tuesday. SiegedSec, a group of self-proclaimed “gay furry hackers,” took responsibility for the attack and claimed they accessed sensitive employee data like social security numbers, home addresses and more.

“We’re willing to make a deal with INL. If they research creating irl catgirls we will take down this post,” SiegedSec wrote in a post announcing the leak on Monday.

The hacktivist group SiegedSec conducted a high profile attack on NATO last month, leaking internal documents as a retaliation against those countries for their attacks on human rights. The group commonly attacks government and affiliated organizations for political reasons, like targeting state governments for passing anti-trans legislation earlier this year.

A spokesperson confirmed the breach to Engadget on Wednesday. “On Monday, Nov. 20, Idaho National Laboratory determined that it was the target of a cybersecurity data breach in a federally approved vendor system outside the lab that supports INL cloud Human Resources services. INL has taken immediate action to protect employee data,” an INL spokesperson said. The lab said it has reached out to authorities for help on how to proceed as it determines how to handle the breach.

INL works as a Department of Energy affiliate researching nuclear reactors, among other projects like sustainable energy. It employs more than 5,000 people.