On the Greek-Macedonian border, clashes erupted on Saturday between Macedonian officers and migrants, who were enraged by the sight of Macedonian authorities erecting a fence along the border.Authorities said 18 Macedonian officers were injured in the brief but intense clashes. Most of them received minor injuries, but two were hospitalized in the nearby town of Gevgelija, Macedonia's Interior Ministry said. There was no official tally of injured migrants, although Macedonian police targeted them with stun grenades and plastic bullets. Doctors from the Red Cross and other non-governmental organizations said they treated 20 people for head injuries and breathing problems.The accidental electrocution at the top of a train carriage of a 24-year-old Moroccan, who suffered severe burns, sparked the unrest among the migrants, many of whom have been stranded at the border since Macedonia decided earlier this month, along with Serbia, Croatia and Slovenia, to let through only those from the "war zone" countries of Afghanistan, Iraq and Syria.The 24-year-old is in serious condition with extensive burns, Greek police said, and he has been transferred to a hospital in the city of Thessaloniki, 80 kilometers (50 miles) south of the border. The man's Moroccan compatriots formed the bulk of about 250 people who started throwing stones at Macedonian police. Also among the 800 stuck at the border are citizens of Algeria, Tunisia, Lebanon, Yemen, Iran, Pakistan, Bangladesh, Somalia and Congo. Greek police didn't intervene to stop the migrants but did at one point interpose themselves to protect their Macedonian colleagues, as the migrants would not target the Greeks. The clash ended in less than an hour when other migrants intervened, holding white clothing as a sign of peace.Macedonian government spokesman Aleksandar Gjorgjiev told the Associated Press that the country has started to erect a fence on its southern border with Greece to prevent illegal crossings and to channel the flow of migrants through the official checkpoint. Gjorgjiev said, "The border will remain open and all migrants from the war-affected zones will be allowed to enter." Government spokesman Gjorgjiev described the situation by mid-afternoon as "calm and stable."The migrants are camped along railway tracks, blocking rail traffic for 11 consecutive days. During the past few days, several migrants have taken shelter from bad weather in parked trains at the station. "I have been here for 10 days with my two sons. We have decided to return to Athens and see what we will do," said Fatemeh, 41, from the Iranian city of Ahwaz. She declined to give her last name for fear of reprisals. "There is no way to return to Iran; only prison awaits us," she said. "We understand that the Syrians, the Afghans and the Iraqis are at war, but we also have a big political problem. There is no freedom in our country."Countries along the migrant route through the Balkans began tightening restrictions two weeks ago by accepting only those fleeing war, causing a backlog of hundreds of people on the Greek-Macedonian border. According to the new limitations, only nationals of Syria, Afghanistan and Iraq are being allowed to cross. The developments on the migrant route come after a Syrian passport was found next to the body of one of the perpetrators of the Nov. 13 deadly attacks in Paris by DAESH. The United Nations decried restrictions on refugees, saying that thousands of refugees are stuck at the main crossing point into Macedonia from Greece as authorities deny entry to some nationalities in contravention of international law. "A new humanitarian situation is developing in Europe that needs urgent attention," Adrian Edwards of the UN High Commission for Refugees (UNHCR) told a news briefing. "The new restrictions chiefly involve people being profiled on the basis of their claimed nationalities," he said.The turmoil in the Middle East and the five-year war in Syria have led many people to flee the conflict to seek security and shelter in a more prosperous and peaceful country. About 858,805 refugees and migrants have arrived in Europe so far this year by sea, primarily to Greece and Italy, while 3,548 have died or gone missing, according to the International Organization for Migration (IOM). Many make the short sea crossing from Turkey, and most of them continue on a long trek through the Balkans toward the promised lands of central and northern Europe.