Tensions escalated around 12:30 p.m. (1030 GMT) near Brussels-Midi railway station, where demonstrators used construction fencing to erect a barricade and threw projectiles at police, public broadcaster RTBF reported.
Police responded by deploying water cannons and tear gas before advancing toward the crowd.
Earlier in the morning, around 100 students and adults, including teachers and trade union activists, had gathered near Brussels Central Station.
The demonstration was initially unauthorized, but protesters later received permission to march toward Brussels-Midi, where a heavy police presence had been deployed and several people were stopped and searched.
Demonstrators chanted slogans against police repression and the federal government’s policies, as Saturday’s mobilization followed clashes between police and students on the sidelines of a trade union demonstration on Oct. 9.
Beyond the unrest in Brussels, a separate demonstration in Liege drew around 250 people, mostly young demonstrators, who gathered outside Liege-Guillemins station before marching peacefully toward the city center, the Belga news agency reported.
Workers and parents joined the procession, with participants voicing concerns over education funding, tuition fees, public transport costs, working conditions and social inequality.
Students highlighted the financial pressures facing young people, saying the need to combine paid work with their studies can make continuing their education difficult and lead some to abandon it.
Some participants also expressed solidarity with Saturday’s mobilization in France against rising living costs, linking their concerns to wider protests over economic pressures and public policy.