The FBI is investigating a hack of its computer network, in an isolated incident that was now contained, the agency said on Friday.

“The FBI is aware of the incident and is working to gain additional information,” the agency said in an emailed statement to Reuters, without providing further details.

CNN, which first reported the incident citing people briefed on the matter, said FBI officials believe it involved computers at its New York office which were used to investigate child sexual exploitation.

It was not immediately clear when the incident occurred. One source told CNN the origin of the hack was still being probed.

The FBI breach is the latest in a series of high-profile U.S. government hacking incidents over the last decade. In late 2020, officials discovered a widespread cyber espionage operation within numerous federal networks by hackers tied to Russian intelligence.

In 2015, the Office of Personnel Management (OPM) announced it too had been hacked and that federal employee records were stolen. The OPM breach was later attributed to Chinese hackers.