[Stranded refugees and migrants try to bring down part of the border fence during a protest at the Greek-Macedonian border, near the Greek village of Idomeni]By Alexandros Avramidis and Lefteris Karagiannopoulos IDOMENI/ATHENS (Reuters) - Macedonian police fired teargas to disperse hundreds of migrants who stormed the border from Greece on Monday as a deeply divided Europe traded barbs over the biggest humanitarian crisis in decades. As frustrations boiled over at restrictions imposed on people moving through the Balkans, migrants trapped on the Greece-Macedonia border tore down a metal gate in the barbed wire fence. A Reuters witness said Macedonian police fired several rounds of teargas into the crowd and onto a railway line where other migrants sat refusing to move, demanding to cross into the country.