PARIS — Protesters filled the streets of Paris and other French cities Thursday, with violence marring several marches, a day after President Emmanuel Macron further angered his critics by standing strong on a bill raising the retirement age that his government forced through parliament without a vote.

Strikes upended travel as protesters blockaded train stations, Charles de Gaulle Airport in Paris, refineries and ports. More than 250 protests were organized across the country and union leaders praised the “significant” mobilization.

In Paris, street battles between police and black-clad, masked groups who attacked at least two fast food restaurants, a supermarket and a bank reflected intensifying violence and drew attention away from the tens of thousands of peaceful marchers.

Police, pelted by objects and fireworks, charged multiple times and used tear gas to disperse rioters. A haze of tear gas fumes covered part of the Place de l’Opera, where demonstrators converged at the march’s end. Police estimated the “radical elements” at some 1,000 people.

Amid the chaos, one police officer was seen falling to the ground with his shield. Colleagues dragged him to safety. Police said he was being treated but didn’t elaborate or say whether there were other injuries.

Violence also marred other marches, notably in the western cities of Nantes, Rennes and Lorient — where an administrative building was attacked and the courtyard of the police station was set afire and its windows broken — and in Lyon, in the southeast.

Thursday’s nationwide protests were the ninth organized by eight unions since January, when opponents still hoped that parliament would reject Macron’s measure to raise the retirement age by two years, to 64. But the government forced it through using a special constitutional measure.

In an interview Wednesday, Macron refused to budge from his position that a new law is necessary to keep retirement coffers funded. Opponents proposed other solutions, including higher taxes on the wealthy or companies, which Macron says would hurt the economy.

The Constitutional Council must now approve the measure. But opponents refuse to give up.

“We are trying to say before the law is enacted … that we have to find a way out and we continue to say that the way out is the withdrawal of the law,” the chief of the moderate CFDT trade union, Laurent Berger, told The Associated Press.

High-speed and regional trains, the Paris metro and public transportation systems in other major cities were disrupted. About 30% of flights at Paris Orly Airport were canceled.

The Eiffel Tower and the Versailles Palace were closed Thursday due to the strikes.

Protesters staged blockades on major highways and interchanges to slow traffic around big cities.

Violence, a recurring issue at protests, has intensified in recent days at small, scattered protests against the pension reform and Macron’s leadership — in contrast to the largely peaceful big demonstrations staged by unions.

Authorities expected violence to be more intense Thursday and Interior Minister Gerald Darmanin had said that 12,000 security forces would be in French streets, with 5,000 in Paris,

Social unrest in France also risks tarnishing the sheen of King Charles III’s first overseas trip as monarch, scheduled next week, with striking workers refusing to provide red carpets and un collected garbage piling up in Paris streets.

Macron insisted Wednesday that the government’s bill to raise the retirement age must be implemented by the end of the year.

Critics attacked him for the statement, describing him as “self-satisfied,” “out of touch” and “offensive.”

Large swaths of society oppose the pension reform.

The Education Ministry said in a statement that about 24% of teachers walked off the job in primary and middle schools on Thursday, and 15% in high schools.

At Paris’ Gare de Lyon train station, several hundred strikers walked on railway tracks to prevent trains from moving, brandishing flares and chanting “and we will go, and we will go until withdrawal” and “Macron, go away.”

“This year perhaps maybe our holidays won’t be so great,” said Maxime Monin, 46, who stressed that employees like him, who work in public transport, are not paid on strike days. “But I think it’s worth the sacrifice.”

Fabien Villedieu, a unionist with SUD-rail, said the strike at France’s railway company SNCF is open-ended. “There are actions every day everywhere … with one, two, three or four protests. One, two, three or four blockades,” he said. “What do we need to do to make the government listen?”

In the northern suburbs of Paris, several dozen union members blocked a bus depot in Pantin, preventing about 200 vehicles from getting out during rush hour.

Nadia Belhoum, a 48-year-old bus driver participating in the action, criticized Macron’s decision to force the higher retirement age through.

“The president of the Republic … is not a king, and he should listen to his people,” she said.