Terence Pike, with the United Nations High Commissioner for Refugees in Croatia, told CNN that Croatian authorities had been prepared to handle only an influx of 500 migrants and refugees a day.
At least two migrants were also injured, Hungarian and Serbian officials said.
Gyorgy Bakondi, Hungarian Prime Minister Viktor Orban’s chief advisor, said the tough response came an hour after the migrants had issued an “ultimatum” to police, demanding to be let through.
In the capital, riot police have taken position around a hotel where migrants are staging a sit-in – refusing to be transferred to an asylum centre.
“There was no disarming or arrests”.
Police said that 36 policemen returned to Croatia in the evening.
Croatia came into the spotlight this week in the ongoing migrant crisis after Hungary closed its border with Serbia with a razor-wire fence and sprayed tear gas to keep the migrants from crossing.
In another display of the divisions within Europe, Hungary called on Croatia to register those seeking asylum rather than allowing them to continue to other countries. They finally gave up and the migrants started running into Croatia. The migrants would prefer the quicker route to Europe through Hungary, instead of taking the longer route to Western Europe through Slovenia.
Croatian leaders put the army on alert after chaos erupted Thursday on the border with Serbia, where thousands of asylum-seekers poured into the country, some trampling each other in a rush to get on the few available buses and trains. “I will not, and cannot, stop those people and they will pass through Croatia”.
“We will not pay the price of someone else’s incapability”, Mr Vulin said. “But, go on. Not because we don’t like you but because this is not your final destination”.
Hungary has stirred up more political angst in Europe by saying it plans more fences along its borders, this time with Romania and Croatia.
Serbia would take Croatia to global courts if the border crossings remained closed, he said.
The Hungarian government do not want to accept any more migrants. “Hungary has been holding its own for the ninth consecutive month”.
There were reports of clashes between desperate refugees from Afghanistan and Syria at the train station in Beli Manastir.
Meanwhile, Hungary began building a fence on its borders with Croatia, similar to the one they completed on their border with Serbia earlier this week.
The United Nations refugee agency warned of a “build-up” of migrants in Serbia.
“Croatia showed it has a heart, both as a country and as people”.