Violence and destruction reportedly broke out in at least three cities, including Paris, Lyon, and Marseille. An estimated 108 police officers were injured as some protesters hurled Molotov cocktails and other projectiles, The Guardian reported. Police, armed with helmets and riot shields, attempted to disperse violent demonstrators with tear gas. At least 291 people were detained.

Interior Minister Gerald Darmanin tweeted that most demonstrators were peaceful.

“If the vast majority of demonstrators were pacifists, of course, in Paris, Lyon, and Nantes in particular, the police face extremely violent thugs who came with one objective: to kill cops and attack the property of others,” Darmanin tweeted. “This violence must be condemned without reservation.”

The ire over the law has not eased in the months following the pension reform law being introduced. As many as 800,000 people took to the streets of France to demonstrate their opposition, according to The New York Times. Laurent Berger, leader of France’s largest labor union, the French Democratic Confederation of Labor, reportedly signaled that the demonstrations against the new retirement age are far from over, saying the protests are a way to continue the fight.

Along with the human toll, businesses, bus stops, and vehicles also reportedly had windows smashed and were defaced with graffiti.

In Marseille, protesters temporarily overran a hotel before being pushed out by police.

French Prime Minister Elisabeth Borne condemned the violent skirmishes, which came on a day that is normally reserved for peaceful trade union protests.

“In many cities in France, this May Day was a moment of responsible mobilization and commitment,” the prime minister tweeted. “The scenes of violence on the sidelines of the processions are all the more unacceptable. Support for our law enforcement.”