By Fatos Bytyci GEVGELIJA, Macedonia (Reuters) - Macedonia moved to cut off the flow of migrants pouring over its southern border with Greece on Thursday, deploying riot police in armoured vehicles and calling out the army under a state of emergency. Authorities said official border crossings remained open, but that they would "reduce illegal border entry to a minimum". A Reuters reporter near the border town of Gevgelija said a column of riot police armed with tear gas and armoured vehicles had shut off passage for several thousand people now stranded in no-man's land.