It had started as a peaceful protest. By the end, streets in Brussels were alight. The rage was aimed at Belgium’s new centre-right government and its planned austerity measures.
A proposed rise in the retirement age, a freeze in wages and public service cuts to meet EU targets brought an estimated 120,000 onto the streets of the capital.
In what was one of Belgium’s biggest labour demonstrations since World War Two, cobblestones and smoke flares were hurled at police who responded with water cannon and pepper spray.
A police spokesman refused to say how many were injured or the number of people detained. One media source said at least 14 people were injured.
Police eventually cleared the area with a charge late on Thursday afternoon.
The march marked the start of a month-long campaign of protests which are set to end with a nationwide strike on December 15.
The government has opened talks with trade union leaders.