Comment: It was mostly teens, and the 'star' they apparently went to see - or who may have organized it - is also just a kid who is renowned on local social media networks for his pranks.
The clashes broke out at the Place de la Monnaie, a square near the Belgian federal opera house in central Brussels. The unrest reportedly began when police officers approached a large group of youths gathered at the square.
The gathering started throwing projectiles at the officers and even forced them to retreat, Belgian broadcaster RTBF reported. The police then called for backup and attempted to disperse the crowd.
Comment: So it escalated quickly then.
A video posted on Twitter shows police officers in riot gear supported by a water cannon moving along the streets of the Belgian capital.
According to other reports, the clashes were triggered by a police attempt to approach a rapper surrounded by a crowd of fans at the Place de la Monnaie. The RTBF reported that a French social network star known as Vargas 92 arranged a meeting with his fans at the square as he was visiting Brussels.
Comment: He's hardly a 'rapper' - he's a kid who has followers on social media because he does funny pranks for 'lulz': fairly harmless stuff too, compared to US 'Jackass' standards anyway.
The rapper, known through his Snapchat and Instagram accounts and adored by teenagers, was scheduled to meet with his fans at around 4pm local time (15:00 GMT). Vargas 92 has almost 600,000 followers on Instagram. According to the Belgian De Morgen daily, the social media figure planned to stage a sort of flash-mob with his fans, but when police approached him the situation quickly escalated.
Belgian Interior Minister Jan Jambon condemned the clashes in his Twitter account, and said that police were doing everything necessary to keep order. This "violence is unacceptable and incomprehensible," he said, adding that federal police are sending reinforcements to their colleagues in Brussels.
In the meantime, local police said that the situation remains tense in the city center. "Police had to take cover at the moment. It is too early to talk about riots but the situation is tense," Brussels police spokesperson Olivier Slosse told VRT news.
The rapper himself was arrested by the police, RTBF reports. According to Belgian media, local law enforcement managed to restore order in the city center after 6 p.m. (local time) (17:00 GMT) as they finally received reinforcements from the federal police.
Comment: The authorities are being ridiculous in their reaction to this particular incident, although it's easy to see why they're hysterical about a large public gathering in the city after going through cycles of terror attacks, martial law, and riots in recent years.
Just last weekend there was a riot nearby when some among the thousands of Moroccan football fans (who have been a large minority community in Brussels for decades) clashed with riot police as they celebrated their 'origin' country's success on qualifying for the 2018 World Cup in Russia.
The 'generalized chaos' out there could well be having cumulative effects, where one thing rolls into another - harmless flash-mobs will soon look, to the authorities, no different from riots, from protests, from pleas for food...