Hundreds of protesters defied a ban on Saturday to march in central Paris against police violence, a week after riots sparked by the killing of a teenager in a Parisian suburb.

Police dispersed the crowd from Paris’s huge Place de la Republique, sending several hundred people towards the wide Boulevard Magenta, where they were seen marching peacefully, Reuters reported. Two people were arrested, Paris police said after the demonstration.

The Paris police department said in a decision published on its website that it had banned the planned demonstration, citing a “context of tensions”.

“We still enjoy freedom of expression in France, but freedom of assembly, in particular, is under threat”, said Felix Bouvarel, a health worker who came to the gathering in spite of the ban which he called “shocking.”

Authorities also banned a demonstration in the northern city of Lille on Saturday, while a march in Marseille took place with a changed trajectory, ordered out of the city center.

Interior Minister Gerald Darmanin said this week that more than 3,000 people, mostly teenagers, had been arrested in six nights of riots that ended a week ago. Some 2,500 buildings were damaged, Reuters reported.

The riots were triggered by the June 27 fatal shooting by a police officer of 17-year-old Nahel M at a traffic stop. A police officer is under investigation for voluntary homicide; his lawyer says he did not intend to kill the teen.

Saturday’s demonstration was called by the family of Adama Traore, a Black Frenchman whose death in police custody in 2016 has been marked by annual protests since. Organizers had sought to move it to central Paris after it was banned in Beaumont-sur-Oise, the Paris suburb where Traore died.

French authorities and politicians including President Emmanuel Macron have denied institutional racism within the country’s law enforcement agencies.