On Wednesday, a shooting incident took place near Clemenceau metro station in Anderlecht, Brussels.
The assailants were armed with a Kalashnikov rifle and stormed into the metro tunnels towards Brussels South Station (Gare du Midi).
No injuries have been reported, media outlets said.
Sarah Frederickx, spokeswoman for the Brussels South police, told Politico: "A shooting took place. The images from the surveillance cameras show that the suspects fled towards the Clemenceau metro station."
In response, the Brussels Intercommunal Transport Company (STIB) suspended services on metro lines 2 and 6 between Hallepoort and Ossegem stations.
Tram lines 4 and 10 were also interrupted between Berkendael and Lemonnier stations.
Additionally, Brussels Midi, Delacroix, and Clemenceau stations were closed by the police.
The police are undergoing a search operation to identify and catch the shooters.