A demonstration against a plan to restrict access through the Brenner Pass between Italy and Austria turned violent Saturday, with Italian police firing teargas at hundreds of protesters throwing stones and firecrackers.

Austria has said it plans to erect a fence at the Alpine crossing it shares with Italy to “channel” people. Within Europe’s borderless Schengen Area, the Brenner Pass is one of the routes that migrants use as they head toward wealthy northern Europe.

Two police officers were injured in the clashes, the head of a local Italian police union, Fulvio Coslovi, told Reuters. He said about 10 demonstrators were being held by police.

Local police in Tyrol, Austria, said more than 600 protesters showed up at the third violent demonstration at the Brenner Pass in just over a month, meeting at the Brenner station in Italy.

TV footage showed clouds of smoke filling the Brenner railway station as groups of demonstrators, their faces masked against the fumes, hurled stones and smoke bombs as they faced off against lines of police in riot gear. Estimates of the number of protesters varied between 250 and 600.

Around 300 Austrian police officers were deployed, but they had not yet had to intervene, a representative said, because the demonstration had taken place exclusively on the Italian side of the border so far.

The Italian newspaper Corriera della Sera reported this week that the protest had been organized by an anarchist group from Trentino in northern Italy and was expected to attract demonstrators from abroad.

Austrian Interior Minister Wolfgang Sobotka said in Rome last month that as many as a million migrants were poised to cross the Mediterranean Sea from Libya this year. Italy says the figure is much lower, although calm summer seas could well bring a surge.

Both Germany and Italy are utterly opposed to Austria’s plan to build a fence at its border with Italy, Italian Prime Minister Matteo Renzi said Thursday after talks with German Chancellor Angela Merkel.