Raids targeting terror suspects continued Sunday across Belgium as riot police used water cannons to disperse a group of self-described fascists damaging memorials in the capital.
At Place de la Bourse, police broke up crowds who authorities said were throwing rocks and bottles and trampling on tributes to the 31 victims of Tuesday's bombings. Some arrests were made, though police didn't immediately say how many.
The crowd gathered in the same place where a peace march had been scheduled for Sunday but was cancelled over security concerns. Officials said police were stretched too thin with their anti-terror operations to dedicate manpower to the march, which was expected to draw thousands of people.
Amid unrest in the capital, police across Belgium carried out 13 house searches Sunday and detained four people for unspecified terrorism incidents, according to the country's federal prosecutor's office.
At least four others were being held on terrorism-related charges in Belgium.
A terror suspect was also detained in the Netherlands today after a request from French authorities, a spokesman in Rotterdam said. A local prosecutor’s spokesman told ABC News that France made the request to the Netherlands Friday to detain a suspect accused of being "involved in planning a terror attack" in France.
While anti-terrorism operations continued across Europe, Belgian Interior Minister Jan Jambon acknowledged decades of neglect had hurt the country's ability to respond to violent extremism despite the government's recent spending on security services.
Jambon said errors were made leading up to last week's attacks in Brussels and the government had invested 600 million euros ($670 million) in the last two years on anti-terror mechanisms, but those investments needed time.
"It is also not because you put the money in now that tomorrow all this is visible on the ground," he said, adding hiring anti-terror specialists could not happen in weeks or months.
According to Belgium’s Crisis Center, 31 victims were killed in the two Brussels attacks, not including three suicide bombers, and 28 of the victims have been identified so far. Victims' nationalities include Belgian, American, Dutch, Swedish, German, French, Chinese, Italian and British.
The Associated Press contributed to this story.