Syrian migrants walk along a railway track to cross the Serbian border with Hungary near the village of Horgos August 27, 2015. (Photo by Marko Djurica/Reuters)

Syrian migrants take a rest in the village of Horgos, near the Serbian border with Hungary August 27, 2015. (Photo by Marko Djurica/Reuters)

Syrian migrants walk along a railway track to cross the Serbian border with Hungary near the village of Horgos August 27, 2015. (Photo by Marko Djurica/Reuters)

A Syrian migrant rests as other migrants walk past along a railway track to cross the Serbian border with Hungary near the village of Horgos August 27, 2015. (Photo by Marko Djurica/Reuters)

Syrian migrants are transported inside a Serbian police vehicle in the village of Horgos near the Serbian border with Hungary August 27, 2015. (Photo by Marko Djurica/Reuters)

Syrian migrants walk along a railway track to cross the Serbian border with Hungary near the village of Horgos August 27, 2015. (Photo by Marko Djurica/Reuters)

Shoes and socks belonging to Syrian migrants are hung to dry near the Serbian border with Hungary, near the village of Horgos August 27, 2015. (Photo by Marko Djurica/Reuters)

Syrian migrants sit inside a tent on a field outside the village of Horgos, near the Serbian border with Hungary August 27, 2015. (Photo by Marko Djurica/Reuters)

Asylum seekers wait inside a train to depart to a refugee camp, after crossing the border into the European Union's visa-free Schengen travel zone, in Szeged, Hungary, August 27, 2015. Hungary made plans on Wednesday to reinforce its southern border with helicopters, mounted police and dogs, and was also considering using the army as record numbers of migrants, many of them Syrian refugees, passed through coils of razor-wire into Europe. (Photo by Bernadett Szabo/Reuters)

Asylum seekers walk to a train to depart to a refugee camp after crossing the border into the European Union's visa-free Schengen travel zone, in Szeged, Hungary, August 27, 2015. (Photo by Bernadett Szabo/Reuters)

An asylum seeker walks to a train to depart to a refugee camp after crossing the border into the European Union's visa-free Schengen travel zone, in Szeged, Hungary, August 27, 2015. (Photo by Bernadett Szabo/Reuters)

Migrants walk on a railway track after crossing the Hungarian-Serbian border near Roszke, Hungary August 27, 2015. (Photo by Bernadett Szabo/Reuters)

A migrant boy walks on a railway track after he crossed the Hungarian-Serbian border near Roszke, Hungary August 27, 2015. (Photo by Bernadett Szabo/Reuters)

A migrant boy cries as he walks on a railway track after he crossed the Hungarian-Serbian border near Roszke, Hungary August 27, 2015. (Photo by Bernadett Szabo/Reuters)

Syrian migrants wait for a bus to register in a camp after they crossed the Hungarian-Serbian border near Roszke, Hungary August 27, 2015. (Photo by Bernadett Szabo/Reuters)

Syrian migrants wait for a bus to register in a camp after they crossed the Hungarian-Serbian border near Roszke, Hungary August 27, 2015. (Photo by Bernadett Szabo/Reuters)

A Syrian migrant girl leans on a border stone on the Serbian border with Hungary near the village of Horgos August 27, 2015. (Photo by Marko Djurica/Reuters)

Syrian migrants walk along a railway track to cross the Serbian border with Hungary near the village of Horgos August 27, 2015. (Photo by Marko Djurica/Reuters)

Syrian migrants walk along a railway track to cross the Serbian border with Hungary near the village of Horgos August 27, 2015. (Photo by Marko Djurica/Reuters)

A girl holding a doll, arrives with others migrants at the refugee center in the town of Presevo, after walking from Macedonia to Serbia on August 26, 2015. At least 2,000 more migrants flooded overnight into Serbia in a desperate journey to try and go on to Hungary, the door into the European Union, a UN official said on August 24. More than 9,000 people, mostly Syrian refugees, have arrived to Serbia those last three days. (Photo by Armend Nimani/AFP Photo)

A migrant from Syria plays with his toddler at a park in Belgrade, Serbia, Thursday, August 27, 2015. Over 10,000 migrants, including many women with babies and small children, have crossed into Serbia over the past few days and headed toward Hungary and the EU Schengen Area, a zone with no internal border checks between member countries. (Photo by Marko Drobnjakovic/AP Photo)

Migrants from Syria sleep at a park in Belgrade, Serbia, Thursday, August 27, 2015. (Photo by Marko Drobnjakovic/AP Photo)

Syrian migrants travel on a bus after arriving on a ferry carrying about 2,500 migrants from the Greek islands to the main port of Piraeus on August 26, 2015 in Athens, Greece. Greece has been overwhelmed this year by record numbers of migrants arriving on its eastern Aegean islands, with more than 160,000 arriving since January. (Photo by Milos Bicanski/Getty Images)

A Greek police officer guides migrants arriving to enter Macedonia, near border with Greece, August 27, 2015. Migrants are trekking from the southern Macedonian border near Gevhelija to the northern border with Serbia on their way to Western Europe. (Photo by Ognen Teofilovski/Reuters)

Syrian migrants cross under a fence as they enter Hungary at the border with Serbia, near Roszke, August 27, 2015. (Photo by Bernadett Szabo/Reuters)

Syrian migrants cross under a fence as they enter Hungary at the border with Serbia, near Roszke, August 27, 2015. (Photo by Bernadett Szabo/Reuters)

Syrian migrants cross under a fence as they enter Hungary at the border with Serbia, near Roszke, August 27, 2015. (Photo by Bernadett Szabo/Reuters)

Syrian migrants cross under a fence as they enter Hungary at the border with Serbia, near Roszke, August 27, 2015. (Photo by Bernadett Szabo/Reuters)

A Syrian migrant runs after crossing under a fence as she enters Hungary, at the border with Serbia, near Roszke, August 27, 2015. (Photo by Bernadett Szabo/Reuters)

Syrian migrants run after crossing under a fence as they enter Hungary, at the border with Serbia, near Roszke, August 27, 2015. (Photo by Bernadett Szabo/Reuters)

Syrian migrant runs after crossing under a fence as he enters Hungary, at the border with Serbia, near Roszke, August 27, 2015. (Photo by Bernadett Szabo/Reuters)

Refugees clamber through barbed wire as they cross from Serbia to Hungary, in Roszke, Thursday, August 27, 2015. Over 10,000 migrants, including many women with babies and small children, have crossed into Serbia over the past few days and headed toward Hungary. (Photo by Darko Bandic/AP Photo)

A young migrant's hair becomes stuck while crawling under a barbed fence with her family at the Hungarian-Serbian border near Roszke, on August 27, 2015. As Europe struggles with its worst migrant crisis since World War II, Hungary has become, like Italy and Greece, a “frontline” state. So far this year, police say around 141,500 migrants have been intercepted crossing into Hungary, mostly from neighbouring Serbia. (Photo by Attila Kisbenedek/AFP Photo)

Syrian migrant family cross under a fence as they enter Hungary at the border with Serbia, near Roszke, August 28, 2015. (Photo by Bernadett Szabo/Reuters)

A Syrian migrant family enters Hungary at the border with Serbia near Roszke, Hungary August 28, 2015. (Photo by Bernadett Szabo/Reuters)

Syrian migrant family cross under a fence as they enter Hungary at the border with Serbia, near Roszke, August 28, 2015. (Photo by Bernadett Szabo/Reuters)

Syrian migrants cross under a fence as they enter Hungary at the border with Serbia, near Roszke, August 28, 2015. (Photo by Bernadett Szabo/Reuters)

Hungarian policemen arrest a Syrian migrant family after they entered Hungary at the border with Serbia, near Roszke, August 28, 2015. (Photo by Bernadett Szabo/Reuters)

Hungarian policemen arrest a Syrian migrant family after they entered Hungary at the border with Serbia, near Roszke, August 28, 2015. (Photo by Bernadett Szabo/Reuters)

Hungarian policemen detain a Syrian migrant family after they entered Hungary at the border with Serbia, near Roszke, Hungary August 28, 2015. (Photo by Bernadett Szabo/Reuters)

Syrian migrants react as they are arrested by Hungarian policemen after they entered Hungary at the border with Serbia, near Roszke, August 28, 2015. (Photo by Bernadett Szabo/Reuters)

A wedding picture of Syrian migrants lays on the ground at the border with Serbia near Roszke, Hungary August 28, 2015. (Photo by Bernadett Szabo/Reuters)