A Gilets Jaunes protest was taken over by black-hooded demonstrators and turned violent in Brussels, forcing authorities to detain 350 people.
The demonstration was intended to be against social injustice on the day of European Parliament elections. But it degenerated into disorder, with some protesters pelting buildings and smashing barricades. Police intervened to disperse the violent demonstrators.
Brussels police spokeswoman Ilse Van de Keere said around 350 people were briefly detained but were released later Sunday.
Police on horseback patrolled the historic center and scuffles broke out in different areas.
About 20 arrests were made after projectiles were thrown at the headquarters of the PS socialist party, according to Le Soir.