Belgian police fired water cannon and tear gas as they moved in Saturday to clear a crowd of several hundred gathered in a park to protest anti-virus lockdown rules.
The defiant, mainly young crowd had assembled for the so-called "Boum 2" protest, organised online, as a follow up to an action that was broken up last month.
Prime Minister Alexander de Croo had urged the crowds to stay away, and hundreds of officers were deployed before the order to clear the park was given
AFP reporters in the Bois de la Cambre, a large park in the city, saw fireworks set off and some missiles thrown before police moved in.
"We see that health measures are not being respected," police announced on Twitter, after drones equipped with loudspeakers called for masks and distancing.
"Brussels police will proceed to clear the area," the tweet read. AFP reporters in the park did not hear an order to disperse.
As the clearance operation began there was little immediate sign of violent resistance from protesters but a dustbin was set on fire as the crowd retreated.
"We're here to protect our freedom. Masks? I don't wear them anymore. I want to be free," said an 18-year-old high schooler from West Flanders, outside the city.
As police cars and armoured trucks with water cannon rolled onto the grass close to the heart of the gathering, the merry-makers chanted: "Freedom, Freedom."
A helicopter and a drone hovered overhead, but the protesters' music all but drowned out police demands for masking and social distancing.
"It's been a year," a 21-year-old woman from the Belgian capital told AFP. "A whole year we can't go out. After a while you need an alternative."
Belgium is under its second national lockdown as a coronavirus prevention measure and bars and restaurants have been shut since late October.
But a vaccination drive is picking up speed and outdoor dining and drinking is due to resume on May 8, and authorities have appealed for calm.
Norton, a 23-year-old cook who has lost his restaurant job, said the plan was not to provoke violence but to demand an end to what he called "illogical" anti-virus measures.
On April 1, a month ago, 2,000 people gathered in the Bois de la Cambre and several were hurt, along with police officers and horses, during clashes.