Amount of police sirend

I (from the Netherlands) have been working in Brussels for the last couple of days and something I noticed is how many police cars with sirens race through the streets in the city here. In 8-10 hours of work I’ve almost counted 50 of them each day. I’ve been living in big city’s for most of my life but never seen/heard so many police cars as this past week. Is there a reason for it? Is there a lot of crime here or is it just some sort of protocol? Just curious.