Tear gas was hurled as protesters, known as yellow vests, took part in a fourth demonstration in Paris on Saturday.

The streets of Paris were filled with thousands of protesters again on Saturday, in what has become French President Emmanuel Macron’s biggest challenge as demonstrations grow more intense.

It’s the fourth rally by the gilets jaunes, or “yellow vests,” protesters wearing the fluorescent jackets required by French law to be in every vehicle.

The unrest started in November, spurred by anger over Macron’s controversial hike in gas taxes – meant to lessen the country’s reliance on fossil fuels and to mitigate the effects of climate change in accordance with the Paris climate agreement.

Over three weeks, the demands of protesters have expanded to include a raise in the minimum wage and a decrease in the retirement age. The rallies have also attracted anarchists, nationalists and other extremists on the far right and left, resulting in deaths, injuries, vandalism and looting.

On Saturday, armored vehicles rolled through cobblestone streets in the French capital — the first time in years that police resorted to that tactic to handle protests, NPR’s Jake Cigainero reported.

About 8,000 police officers were on the ground in Paris – nearly twice as many as last week. They made hundreds of preventative arrests, following orders to engage with and remove violent demonstrators instead of avoiding direct confrontation as they did last week, NPR’s Eleanor Beardsley reported.

Near the Arc de Triomphe, police fired tear gas grenades and water cannons to push back demonstrators. Instead of retreating, protesters moved closer in once the smoke cleared, and the scent of tear gas wafted through the streets.

More than 700 people were detained, according to AFP. Video showed protesters being searched by law…