JEZEVO, Croatia — Open doors for refugees in Croatia began to close Thursday as the country quickly became overwhelmed with a stream of asylum seekers trudging toward Western Europe after being turned away from Hungary with tear gas and water cannons.

With the crisis building – and the European Union still divided over its response – European Council President Donald Tusk called an emergency meeting for Wednesday. For months, EU leaders have been unable to agree on how to deal with the hundreds of thousands of people flooding their borders.

A day earlier, thousands of men, women and children started to arrive in Croatia from Serbia after their old route was blocked by Hungary’s 108-mile border fence.

At first they were met with open arms and promises of help to speed them on their journey as many seek final haven in countries such as Germany and Sweden. But the friendly reception turned harsh – a measure of how the vast numbers of people fleeing war and poverty are quickly outstripping a divided Europe’s ability to accommodate them.

“Croatia will not be able to receive any more people,” Croatian Interior Minister Ranko Ostojic said Thursday at a packed railway station just over the border from Serbia, Reuters reported.

It was not immediately clear what border rules could be imposed by Croatia. The state-run news agency Hina said Croatia’s president, Kolinda Grabar-Kitarovic, asked military commanders to be ready, if needed, “to protect the national borders from the illegal migration.”

Any significant tightening could prompt refugees traveling north from Greece – the first European foothold for many – to consider new routes through the Balkans, possibly through some of the European Union’s poorest members such as Bulgaria and Romania.

Less than 24 hours earlier, Ostojic had said that authorities had “complete control” over the situation.

At least 7,300 people had crossed into Croatia by Thursday, and hundreds more were arriving every hour.

Blue-clad Croatian riot police lined up at the rail station to try to hold back the increasingly angry crowd. Thousands of people waited in vain for a train to take them onward to the capital, Zagreb, and as the sweltering morning turned to afternoon with no relief in sight, a group of hundreds of people set off down the tracks on foot.

But it was unclear how far they would make it, because Ostojic said that Croatia had decided to bar their further passage. They will either have to apply for asylum in Croatia or be considered there illegally, he said.

The shifting currents highlighted both the make-or-break resolve of the asylum seekers and the growing friction facing Europe, which has failed to rally around a coordinated policy for the unprecedented influx.

So far it has agreed to spread only 40,000 asylum seekers across 22 EU nations. Plans for another 120,000 have been bitterly opposed by central and eastern European nations.

Policymakers have been caught off-guard in recent weeks as the numbers have swelled.

On Thursday, one of the officials who helped spark the onslaught resigned. Germany’s top migration official, Manfred Schmidt, stepped down for “personal reasons” less than a month after his agency posted a message on Twitter that had far-reaching consequences.

The announcement that Germany would no longer deport Syrian asylum seekers to the EU country they entered – often Greece or Italy – helped fuel fresh waves of refugees who saw Germany as opening its arms.

Germany is now expecting up to 1 million asylum seekers this year alone.

With Europe bitterly divided, bigger and richer countries are increasingly lashing out at poorer partners that have so far refused to take in many people.

“Germany is helping. The question is: Who is helping Germany?” German Vice Chancellor Sigmar Gabriel asked in a video released Thursday. He accused other countries of taking EU money, then “hiding in the bushes when they have to take responsibility.”

Hungary has so far taken the harshest measures to block the refugee tide, using teargas, pepper spray and water cannons to repel a crowd of migrants on Wednesday who had approached its newly constructed razor-tipped border fence.

“We don’t like the fence,” said the Hungarian government’s chief spokesman, Zoltan Kovacs. “But it seems to be working to protect the country’s borders, to stop illegal migration. Obviously we are going to continue with that: keeping the fence, protecting the fence by police.”

Hungarian authorities said the number of people crossing into their nation had all but dried up: 277 on Wednesday, down from 9,380 on Monday. Some of the few asylum seekers on Wednesday who made it into Hungary said their applications were summarily denied and that they were kicked back into Serbia.

By Thursday, the camp along the Serbian-Hungarian border was quickly emptying as asylum seekers paid 20 euros apiece to get on buses that were ferrying them to the Croatian border. Kids rode free.

“Violence is not the solution,” said the top EU official in charge of refugees, Dmitris Avramopoulos, after meetings Thursday in Budapest with senior Hungarian officials.

“The majority of people arriving in Europe are Syrians. They are people in genuine need of our protection,” he added. “There is no wall you would not climb, no sea you wouldn’t cross if you are fleeing violence and terror. I believe we have a moral duty to offer them protection.”

Asylum seekers vowed that they would reach Western Europe no matter the obstacles thrown in their path.

“We hit a stone and we flow around it,” said Arazak Dubal, 28, a computer programmer from Damascus, who had been on the road for 18 days on Wednesday.

He and his three companions reached Belgrade only to discover on Facebook and WhatsApp that the Hungarian border was closed to refugees.

“So I went to Google Maps, and here we are,” said Dubal, huffing in the hot afternoon as he trudged across the farm fields.

The Wednesday clashes at the Hungarian border were the first between security forces and migrants since police used stun grenades to stop refugees from crossing into Macedonia from Greece almost a month ago.

At the United Nations, Secretary General Ban Ki-moon called Hungary’s border crackdowns “unacceptable.”

Croatian authorities had been taking asylum seekers from the border by bus to a refugee processing camp outside Zagreb, where they would be officially registered.

What happens after Zagreb was uncertain.

Croatian officials initially said they would probably allow the migrants to continue their journeys by bus and train to Slovenia, Austria, Germany and beyond. But a Croatian effort to create a joint corridor with Slovenia to funnel migrants directly into Austria hit a snag on Thursday, after Slovenian authorities said they would instead bolster their presence at their Croatian border.