This May 2014 video says about itself:
In an effort to suppress May Day protests, Turkish Prime Minister Recep Tayyip Erdogan shut down all public transportation and roads around Taksim square [in Istanbul]. But clashes broke out all over the city after a reported 40,000 riot police used tear gas, water cannons and rubber bullets to crack down on protesters.
From daily The Morning Star in Britain today:
Workers’ in Turkey’s Van province banned from holding May Day celebrations