The Naval Criminal Investigative Service is investigating a giant nude photo sharing ring inside a private Facebook group for male Marines, the AP reports.

Hundreds of US Marines were allegedly involved, uploading naked pictures of more than two dozen female service members and vets onto a 30,000-person private Facebook group called “Marines United.” Some of the naked photos were taken without the women’s knowledge or possibly hacked from their personal data, and many of the posts included sensitive information, including the subject’s name, rank, and social media accounts.

The photo scandal was uncovered by two nonprofit news organizations, War Horse and the Center for Investigative Reporting. War Horse founder and Marine veteran Thomas Brennan reported the harassment to the Marine Corps, which quickly launched an investigation.

“We are thankful that Thomas Brennan, a Marine veteran, notified the Marine Corps and NCIS about what he witnessed on the ‘Marines United’ page,” Capt. Ryan E. Alvis, Marine Corps spokesman, told the AP. “It allowed us to take immediate action to have the explicit photos taken down and to prepare to support potential victims.”

At least two people associated with the photo sharing ring have been fired, according to Brennan, and the investigation is ongoing. Both the Facebook group and the Google Drive link associated with the ring have been deleted by the companies at the request of the Marine Corps, according to NPR. 

“The Marine Corps is deeply concerned about allegations regarding the derogatory online comments and sharing of salacious photographs in a closed website,” Alvis continued. “This behavior destroys morale, erodes trust, and degrades the individual.”