Police say about 27,000 migrants and refugees have entered into Croatia since the surge started.
Authorities are setting up tents for migrants to find shelter from the rain and cold as they expect more to arrive from Serbia in the coming days.
Hundreds of people surged toward a train at the Croatian border hoping it would take them to Austria. Police had no luck holding back the crowd as they were overwhelmed by migrants trying to climb through the windows of the packed carriages.
Hungary, which closed its border with Serbia on Sept. 15, erected another steel barrier at the Beremend border crossing from Croatia to try to slow the flow of migrants. But they kept coming.