Moroccan police arrested on Thursday three people it had sought in a manhunt over the killing of two female tourists from Norway and Denmark in a suspected militant attack in the Atlas Mountains.
The bodies of Louisa Vesterager Jespersen, 24, from Denmark and Maren Ueland, 28, from Norway, were found on Monday in an isolated area near Imlil, on the way to Toubkal, North Africa's highest peak and a popular hiking destination.
The authorities had said a suspect arrested in tourist hub Marrakech on Tuesday was a member of a militant group, without naming the organisation.
Danish intelligence said earlier on Thursday that ISIS could be behind the killings.
Three more suspects sought by police had also been arrested in Marrakech, the Moroccan Bureau for Judicial Investigations said in a statement.
The evidence discovered so far pointed to a terrorist motive, it said.
Preliminary investigations of a video shared on social media purporting to show the killing of one of the tourists had found that it was shot in a different place from where the bodies were found, a police source told Reuters.
"The video and preliminary investigation according to the Moroccan authorities indicate that the killings may be related to the terrorist organisation ISIS," the Danish intelligence service said in a statement.
"This is a case of an unusually bestial killing of two totally innocent young women," it said.
"This is a brutal and meaningless attack on innocent people, which we react to with disgust and condemnation," said Norwegian Prime Minister Erna Solberg in a statement.
Morocco's Central Bureau for Judicial Investigations, established in 2015, says it has so far broken up 57 militant cells, including eight in 2018.