Belgian Police say a person's been "neutralised" by soldiers at Brussels Central Station after a small explosion.
Local media says the individual was wearing an explosive belt.
The area has been evacuated and trains have been stopped.
Officers say the situation is under control and there are no other casualties.
Sky's Ed Brown said there were a lot of police vehciles and military officers in the area.
This unverified picture posted on Twitter claims to show the suspected explosion:
Twee luide ontploffingen in Brussel Cebtraal. Voor mijn neus. Dan snelle knallen na elkaar. pic.twitter.com/FDqVAjgGYg— Rémy Bonnaffé (@remybonnaffe) June 20, 2017