ZAGREB, Croatia — Croatian authorities have banned visits to nursing homes and hospitals in the Croatian coastal town of Zadar following an outbreak of the new coronavirus at an exhibition tennis tournament there.

Tennis players Grigor Dmitrov from Bulgaria, Borna Coric from Croatia and two more people have tested positive after participating in the Adria Tour event organized by top-ranked Novak Djokovic of Serbia.

Authorities said Monday that dozens more tests are underway in Zadar, while Croatia’s state HRT television reported that Prime Minister Andrej Plenkovic also will be tested after visiting the event.

Djokovic’s team said he has returned to Serbia and was tested there, while the event has been canceled.

Croatia has reopened in hopes of salvaging the summer tourism season along the Adriatic Sea coast. The European Union nation will hold a national election on July 5.