PARIS, BUENOS AIRES (Reuters) – French President Emmanuel Macron said on Saturday that the wave of violence and vandalism in Paris on Saturday could not be justified as rioters ran amok across the central parts of the French capital, torching cars and buildings, looting shops, smashing windows and clashing with police in the worst unrest in more than a decade.

“No cause justifies that security forces are attacked, shops pillaged, public or private buildings set on fire, pedestrians or journalists threatened or that the Arc de Triomphe is sullied,” Macron told a news conference in Buenos Aires, where he was attending the G20 summit.

Declining to take questions after a day of rioting in Paris, he said those who had carried out the violence merely sought to spread chaos. He said he would convene a meeting of senior ministers has soon as he returns to discuss how to respond.

The French authorities were caught off guard by the escalation in violence after two weeks of nationwide protests against fuel taxes and living costs, known as the “yellow vest” movement after fluorescent jackets kept in all vehicles in France.

In Paris, police said they had arrested almost 300 people while 110 were injured, including 20 members of the security forces. Police fired stun grenades, tear gas and water cannon at protesters at the top of the Champs-Elysees boulevard, at the Tuilleries Garden near the Louvre museum and other sites.

In some areas there was virtually no police presence at all, as groups of masked men roamed in the shadows of the capital’s fabled landmarks and through its fanciest shopping districts, smashing the windows of designer boutiques.

The popular rebellion erupted out of nowhere on November 17 and has spread quickly via social media, with protesters blocking roads across France and impeding access to shopping malls, factories and some fuel depots.

On Saturday, some targeted the Arc de Triomphe, chanting “Macron Resign” and scrawling on the facade of the towering 19th-century arch: “The yellow vests will triumph.”

Protesters smashed the windows of a newly opened flagship Apple Store and luxury boutiques of Chanel and Dior, where they daubed the slogan “Merry Mayhem” on a wooden board.

Close to the Place Vendome, Christmas trees decorating the streets were upended, piled in the middle of an avenue and set ablaze, prompting chanting from scores of protesters.

Order appeared to have been restored late in the evening, although small groups were still at odds with police near the Champs Elysees.

Authorities said violent far-right and far-left groups had infiltrated the yellow vests movement. Interior Minister Christophe Castaner said most of those arrested were regular protesters who had been egged on by the fringe groups.

The protests began as a backlash against Macron’s fuel tax hikes, but have tapped into a vein of deep dissatisfaction felt towards the 40-year-old’s economic reforms, which many voters feel favor the wealthy and big business.