RABAT, Morocco (AP) — Moroccan prosecutors have filed preliminary terrorism charges against 15 people who are suspected of links to the killing of two Scandinavian women in the Atlas Mountains.

Morocco's public prosecutor said in a statement that the charges include forming a gang to prepare and commit terrorist acts and premeditated murder. Three of the suspects faced additional charges for allegedly urging the others to commit acts of terrorism.

The women, one from Denmark and one from Norway, were found dead in a remote mountain region on Dec. 17. Authorities have described the slayings as an alleged attack by followers of the Islamic State group.

The 15 suspects were referred on Sunday to an investigating judge who handles terror-related cases. More suspects are expected to be charged in the coming days.