Copenhagen police says they have arrested four people recently returned from Syria and suspected of having been recruited by the Islamic State group to commit terror.
Police tweeted Thursday ammunition and weapons were found in a related search.
Authorities have not released more details on the identity of the suspects who will be seen by a judge on Friday.
Justice Minister Soren Pind said, “We know that people who have fought for IS in Syria or Iraq may pose a specific security threat against Denmark."
Danish forces have been on alert since a shooting at a free speech event in a Copenhagen synagogue in February 2015. Danish intelligence service PET believes that as of last October, over 125 people have returned to Denmark after joining IS in Iraq or Syria.