ATHENS, Greece (AP) — Thousands of people marched through central Athens on Friday to mark the 50th anniversary of a pro-democracy student uprising that was violently put down by the military dictatorship ruling Greece in 1973.

The annual march started from the Polytechnic campus, which was the headquarters of the uprising, and headed toward the U.S. Embassy. America is still widely blamed in Greece for supporting the 1967-74 rightwing dictatorship during the Cold War.

Many of the protesters Friday carried Palestinian flags, while the march was preceded by a group of students carrying a blood-spattered Greek flag that flew at the Polytechnic during the events of 1973.

The march is often marred by rioting by far-left supporters and thousands of police were on duty Friday to maintain the peace.

Tensions have been simmering in recent days, after the fatal police shooting of a Roma teenager following a high-speed car chase in central Greece.

Police were stationed outside the embassy building, located just off a major Athens thoroughfare, to prevent protesters from getting close.

The Polytechnic uprising, which came a year before the collapse of the dictatorship, was crushed by the Greek military and security forces who used a tank to smash through the campus gates.

Dozens of people were killed by government forces before and during the violent crackdown, though the precise number of victims is still a matter of dispute.