The World Anti-Doping Agency (WADA) announced today that Russian hackers gained access to its database and viewed information on athletes involved in this year’s Olympic games. The agency claims the state-sponsored group Fancy Bear is behind the attack, although it doesn’t clarify how that attribution was made.

The accessed data included medical information, like Therapeutic Use Exemptions issued by International Sports Federations and National Anti-Doping Organizations. The group has reportedly released some of this data and threatened to release more.

The attackers reportedly relied on spear phishing emails to gain access to the database and eventually used credentials specifically made for the Rio Olympic games. WADA didn’t say how long the group had access or when it first gained entry. Since the incident, WADA is conducting vulnerability tests and bringing in law enforcement to conduct an investigation.

Fancy Bear was also reported as the group behind this summer’s attack on the Democratic National Committee. In that case, three security firms independently verified the attribution and concluded the attack’s motives related to Russia and the country’s interests. Russia was separately tied up with a doping scandal this summer, which ultimately resulted in 119 members of its Olympic team being banned from participating in the games.