HORGOS, Serbia >> Baton-wielding Hungarian riot police unleashed tear gas and water cannons against hundreds of migrants Wednesday after they broke through a razor-wire fence and tried to surge into the country from Serbia. Crying children fled the acrid smoke and dozens of people were injured in the chaos.

With their path blocked, hundreds of other asylum-seekers turned to a longer, more arduous path to Western Europe through Croatia, where officials said 1,300 had arrived in a single day — a number that was sure to grow.

On the sealed border into Hungary, frustrated men — many of them war refugees from Syria and Iraq — hurled rocks and plastic water bottles at the helmeted riot police as they chanted "Open" Open!" in English. Children and women cried as the young men, their faces wrapped in scarves, charged toward the police through thick smoke from tear gas and tires set on fire by the crowd.

"We fled wars and violence and did not expect such brutality and inhumane treatment in Europe," shouted an Iraqi, Amir Hassan, his eyes red from tear gas and his hair and clothing soaked after being hit by blasts of water cannon spray.

"Shame on you, Hungarians," he shouted pointing in the direction of the shielded Hungarian policemen who were firing volleys of tear gas canisters directly into the crowd.

Around him, women screamed and wailed, covering their faces with scarves as they poured bottled water into their sobbing children’s eyes to relieve the stinging. Children gasped from the gas; blood streamed down the face of one man as he ran from the melee, carrying a small child. People fainted from the noxious plumes of tear gas, including one woman who collapsed while holding a baby.

At least two people were seriously injured and 200 to 300 others received medical care for tear gas inhalation and injuries such as cuts, bruises and burns, said Dr. Margit Pajor, who treated people at a medical center in Kanjiza, Serbia.

U.N. Secretary-General Ban Ki-moon expressed "shock" at the behavior of Hungarian police, calling it unacceptable. Referring to Syria, he said: "People facing barrel bombs and brutality in their country will continue to seek life in another."

Hungarian authorities insisted they acted legitimately in self-defense, describing the migrants as violent and dangerous.

"We will employ all legal means to protect Hungary’s border’s security," said Gyorgy Bakondi, homeland security adviser to Prime Minister Viktor Orban. "We will not permit violent, armed, aggressive attackers to enter."

The ugly developments in Europe’s migrant crisis took place after some of those massed in Serbia broke through a gate. They and hundreds of others had grown desperate after Hungary sealed off its border with Serbia with a razor-wire fence the day before to stop the huge numbers of migrants entering Hungary, which lies on a popular route to Western Europe.

More than 200,000 have entered Hungary this year alone, turning the country into one of the main entry points into Europe for the rising numbers of people fleeing war and persecution in Syria, Iraq and elsewhere.

Orban said Wednesday he plans to also build stretches of fence along the border with Croatia. A day earlier his government said it was also extending the fence along a stretch of its border with Romania. Both Croatia and Romania, like Hungary, are members of the EU, and the moves are straining ties with those allies and herald the unusual prospect of fortress-like barriers between EU states.

After the clashes with police, chaotic scenes also erupted as some private groups delivered aid in trucks. People fought over food, water and clothing, with no Serbian policemen or anyone else to establish order.

It was clear that Hungary’s ties with Serbia were facing deep strains.

Hungary’s foreign minister, Peter Szijjarto, decried what he called "brutal attacks" by the migrants against Hungarian police and asked Serbian authorities to crack down on the migrants on its soil.

Serbia said it would send more police to the border to separate the migrants from Hungarian police. But Serbian Prime Minister Aleksandar Vucic, on a visit to the United States, condemned the "brutal treatment" of migrants by Hungarian police.

"We will not allow anyone to humiliate us and we will not allow anyone to throw tear gas on Serbia’s territory," Vucic said.

Meanwhile, Serbian state television said three of its staff members reporting at the border were beaten by Hungarian police with batons and that their equipment was broken.

Radio-Television Serbia said that Hungarian police pushed a cameraman against the wall and then beat him on the head and back and then smashed his camera. A reporter’s arm was also hurt. The beatings occurred while the journalists stood between police and the migrants even though they identified themselves as journalists, the broadcaster said.

Hungarian authorities said they have arrested 519 migrants who tried to cross the border since tough new laws went into effect Tuesday that make it a crime to cross from Serbia anywhere other than at legal checkpoints. Authorities launched 46 criminal prosecutions and found nine people guilty, the first convictions based on the new laws.

The asylum-seekers, who were escorted into court in handcuffs, were expelled from Hungary and banned from re-entering the country for either one or two years. They were provided with lawyers and translators.

Syrian President Bashar Assad blamed Europe for the crisis, saying it was a direct result of the West’s support for extremists in Syria over the past four years.

In an interview with Russian media, Assad accused Europe of supporting "terrorism" and providing "protection for terrorists, calling them moderates."

Earlier in the day, Hungary’s foreign minister denied the closed borders and tough new laws signaled callousness toward refugees, repeating the government’s claim that most of those entering Hungary are actually economic migrants.

"Based on our history, we are always in solidarity with the refugees," Szijjarto told The Associated Press in an interview. "What we’re saying is that we cannot accept economic migrants because we cannot bear the burden of that."

Some asylum-seekers trapped at the border were confused about whether to keep waiting or to try to enter the EU through Croatia, where there are still mines left over from the Balkan wars. A de-mining expert was killed earlier this week when one of the mines exploded, but not in the region where the migrants are expected to travel.

Croatia’s Mine Action Center says there are still 500 square kilometers (193 square miles) of suspicious areas throughout the country, but all have been clearly marked.

De-mining experts have been working recently in areas where the migrants will pass to remove remaining mines.

"I don’t know what to do — stay here or try some other way to cross the border," said Ahmed Sami from Aleppo, Syria. "We walked and traveled for hundreds, thousands of kilometers only to be stopped meters from the European Union. My wife and children cannot stand on their feet any more. This is tragic."

Croatian Prime Minister Zoran Milanovic criticized Hungary’s decision to seal its border with Serbia and said Croatia will not do the same.

"We are ready to accept these people, regardless of their religion and the color of their skin, and direct them to the destinations where they wish to go, Germany and Scandinavia," Milanovic told lawmakers in Parliament.

Elsewhere in Europe, migrants remained on the move.

Greek police said some 5,000 people trying to reach Western Europe crossed the country’s northern border with Macedonia over the 24-hour period from Tuesday morning to Wednesday morning.

Gera reported from Budapest, Hungary. Associated Press reporters Mike Corder in Roszke, Hungary; Pablo Gorondi and Alex Kuli in Budapest; Darko Bandic in Tovarnik, Croatia; Jovana Gec in Belgrade, Serbia; and George Jahn in Vienna contributed to this report.