COPENHAGEN, Denmark — Authorities arrested three more suspects Thursday in the deaths of two Scandinavian university students who were killed in Morocco’s Atlas Mountains, while the Danish intelligence agency said the women’s slayings “may be related” to the Islamic State group.

The three suspects were arrested as they tried to flee Marrakech on a bus, Moroccan national security spokesman Boubker Sabik said. Authorities have said they consider the killings a terrorist act, and Sabik said officials are investigating if the three have extremist ties.

Another suspect was arrested Tuesday. Moroccan prosecutors said he had affiliations to an extremist group, without naming it. No other suspects besides the four now held are being sought, Sabik said.

28-year-old Maren Ueland from Norway. AFP - Getty Images

Danish Prime Minister Lars Loekke Rasmussen confirmed the identities of the victims, 24-year-old Louisa Vesterager Jespersen, of Denmark, and Norwegian citizen Maren Ueland, 28. The University of South-Eastern Norway said both women were students at its campus in Boe, southern Norway.

“What should have been a holiday trip turned into a nightmare” for the women, Loekke Rasmussen told reporters in Denmark.

The women’s bodies were found Monday in a remote region of the Atlas Mountains not far from a village that often is the starting point for treks to Mount Toubkal, North Africa’s highest peak.

Moroccan media outlets reported that investigators have video surveillance footage showing three suspects putting up a tent near the victims’ tent and leaving the area after the slayings. Other tourists found the women with stab wounds in their necks and alerted police, according to national media in Morocco.

Imlil is a tourist village in the High Atlas range. Fadel Senna / AFP - Getty Images

The killings were “politically motivated and thus an act of terror,” Denmark’s Loekke Rasmussen said, without identifying the potential motives. “There are still dark forces that want to fight our values” and “we must not give in.”

In neighboring Norway, Prime Minister Erna Solberg said terrorism “is not the only lead that is being investigated in Morocco,” but the case “emphasizes the importance of combating violent extremism.”

“We trust that Moroccan authorities are doing their utmost to arrest those responsible for the murders,” she said at a news conference.

Preliminary findings from the investigation “indicate, according to Moroccan authorities, that the killings may be related to the terrorist organization the Islamic State group,” Denmark’s domestic security agency said in a statement to The Associated Press.

The slayings have shocked Morocco, a popular tourist destination where attacks on foreigners are extremely rare. In the capital of Rabat, government spokesman Mustapha El Khalfi said Morocco condemned “this terrorist, criminal act.”

“It is an unacceptable act that does not fit with the values and traditions of Moroccan people nor the traditions of the area where the crime happened,” Khalfi said Thursday. It is a denounced, condemned act.”

A national security official who asked not to be named because he wasn’t authorized to speak to the media identified the suspects to The Associated Press as Abdessamad Ejjoud, born in 1993; Younes Ouziad, born in 1991; and Rashid Aftati, born in 1986. They had knives and slingshots when they were arrested, the official said.

Morocco is generally considered safe for tourists but has battled with Islamic extremism for years. More than a thousand Moroccans are believed to have joined the Islamic State group.

An anti-terrorism rally is being planned for Saturday in Rabat.