SARAJEVO, Bosnia-Herzegovina (AP) — Two people were killed and 18 others were hurt in a clash among migrants in the northwestern part of the country, Bosnian police said Thursday.

The violence took place late Wednesday in the northwestern town of Bihac, police said. A police patrol came to the scene following a call from a Bihac resident. The injured migrants, including 10 seriously, have been transferred to a local hospital.

It wasn’t immediately clear what sparked the clashes, but the migrants’ long journeys and uncertain future often lead to tensions among them.

Migrants have flooded into the northwestern Bosnian town because it’s located near the border with European Union member nation Croatia.

Thousands of people who fled poverty or violence in their home countries have been stuck in Bosnia and other Balkan countries as they try to reach Western Europe. Many migrants have been sleeping rough or in makeshift camps.

Aid workers have voiced fears over conditions that migrants face as cold weather approaches with the end of summer.