German prosecutors are charging four men with the organized distribution of images of child sexual abuse over their involvement in a darknet site called Elysium.

The men from Germany and Austria, aged 40 to 62, are accused of operating the site until it was switched off by authorities in June 2017.

In a statement Tuesday, Frankfurt prosecutors said the material hosted on the site included pictures and videos of grave sexual abuse of very young children. Some of the material was created specifically for the site and at least one suspect is accused of participating in the sexual abuse of two children under 7.

Prosecutors said their investigation into the 111,000 registered users of the site is ongoing.

Darknet sites can be visited only by using special software.