Europe's migrant crisis took a worrying turn over the weekend, after Macedonia restricted its border and a suspected arson attack took place at a planned refugee shelter in Germany.

Around 20 to 30 people cheered as a shelter in Bautzen, Saxony, burned on Saturday night, with some members of the mob disrupting the work of firefighters called to the scene, according to Agence France-Presse. Police found traces of fire accelerant at the scene and suspect the fire was the result of an arson attack. Two men were detained for defying police orders.

The news prompted a sharp response from government officials, who described the attack as "disgusting." It followed an attack two days before in Clausnitz, Saxony, where a bus carrying 20 asylum-seekers was attacked by a group of about 100.

Police chief Uwe Reissmann said criminal charges against the Clausnitz mob had not been ruled out. Reissmann caused outrage in his comments by saying charges against the migrants had not been ruled out either, who were sighted filming the scene and making gestures.

"I am horrified that you again have scenes in Germany in which a mob applauds because a refugee shelter is burning," said Aydan Özoğuz, head of integration issues for the German government. "Something is going very wrong in Saxony."

In Greece, a police official reported to AFP Sunday that Macedonian officials have closed the Greece-Macedonia border to Afghan migrants, with Iraqis and Syrians allowed in. 

Balkan nations had previously only allowed Afghan, Syrian and Iraqi migrants through, describing others as "economic migrants." The migrants would travel through the Balkans to apply for asylum in Northern Europe, but this route appears to be in crisis.

The Greek official claimed that Macedonia had justified the decision by stating that Serbia had taken similar measures, which in turn had restricted access due to a new daily cap on asylum-seekers imposed by Austria from Friday. The move has had a ripple effect throughout the Balkans.

A Greek government source told AFP that it had not been told of the change by Macedonia. "Greece condemns any unilateral action" with regard to the migrant crisis, they said.