Macedonian special police forces have fired stun grenades to disperse thousands of migrants stuck on a no-man?s land with Greece, a day after Macedonia declared a state of emergency on its borders to deal with a massive influx of migrants heading north to Europe.

The crowd of some 3,000 migrants who spent night out in the open made several attempts to charge Macedonian police early Friday after the border was shut to crossings the previous day. At least four people were injured in the melee.

Police backed by armored vehicles also spread coils of razor wire over rail tracks used by migrants to cross on foot from Greece to Macedonia.

Greece has seen an unprecedented wave of migrants crossing clandestinely to its islands from the nearby Turkish coast.