Italian police have detained three Kosovars and a minor in Venice on suspicion of being part of a jihadist cell.

Venice Mayor Luigi Brugnaro said all those detained in the early morning sweep Thursday had regular residency permits to live in Italy. The nationality of the minor is not known.

He said in addition to the detentions, police searched 12 sites in Venice’s center, Mestre and nearby Treviso.

Italian police have made several arrests in recent years of suspected Islamic extremists, including on allegations they were recruiting fighters for jihad in Syria and Iraq, were radicalizing others or were plotting attacks domestically.