Story highlights The four suspects allegedly joined ISIS in Syria "to commit terrorist acts"

They were arrested in the Copenhagen metropolitan area, police say

Authorities seized weapons and ammunition in connection with the arrests

(CNN) Some 2,000 miles separate Denmark and Syria, but they were connected Thursday when Danish authorities arrested four people suspected of having enlisted in ISIS in Syria. Authorities also seized weapons and ammunition related to those arrests.

Copenhagen police and Denmark's security and intelligence service, known as PET, worked together to make the arrests in the Copenhagen metropolitan area, according to a police statement.

Copenhagen police spokesman Mads Jensen told CNN that authorities found weapons and bullets in a related search. But it was not immediately clear the amount discovered, or whether the suspects were actively plotting a terrorist attack.

Copenhagen police declined "for the sake of further investigation" to specify what led to the arrests or the identities of those detained, even their genders and nationalities.

The four are suspected of having enlisted with ISIS in Syria, which has become a magnet for would-be jihadists.