Violence erupted across Europe on Saturday as leftist demonstrators smashed windows, set fires and confronted a massive police force that deployed water cannons but could not slow down the discontent across a continent that has drifted leftward in recent years.

French Interior Minister Laurent Nuñez announced more than 1,000 rioters had been arrested as Paris became the epicenter of the unrest and transformed one of Europe's most iconic capitals into an armed fortress.

"Violent individuals have no place in the marches," the Paris Police Department said in a social media post. "The objective is clear: to prevent troublemakers from joining the procession, and to ensure the safety of the demonstrators."

Nunez said security forces faced an “extremely high level of violence ... with projectiles constantly being thrown and mortar fireworks fired.”

The unrest spread elsewhere as violent clashes broke out in Rome and Albania's capital of Tiranë, where government buildings were set ablaze.

More than 70,000 police were deployed in France as cities prepare for a weekend of more protesting and marches. About 110,000 demonstrators marched in Paris.

More than 500,000 protested in the streets last weekend, the Associated Press reported.