Police swooped on the West Station, known as the Gare de l’Ouest station, in Molenbeek-Saint-Jean this afternoon. The man launched his savage attack at around 3pm local time (4pm UK time). Shocking footage posted on social media shows police officers arresting a person lying near a pool of blood on a train.
Officers disarmed the man and he was arrested and taken into custody.
Witnesses described scenes of “panic” on the train where the attack occurred.
Belgian news website lesoir.be reported that several people had been injured in the knife attack.
One person claimed a woman had been stabbed in the throat.
And another source claimed at least one woman was stabbed in the neck.
Belgian news website La Libre reported that the attack began as a dispute between a man and his ex-girlfriend.
The publication said he attacked her and when onlookers tried to intervene he turned on them.
The office said it had requested the confiscation of video footage taken at the scene and said: “No further announcements will be made about the ongoing investigation.”
Police told Dutch outlet BRUZZ: “There has been a case of aggression in a metro train on line 2-6, near West Station.”
The Federal Police Railways Police Directorate are investigating.
Authorities have not yet released details on the condition of the victims.
Underground services in the Belgian capital were interrupted by the incident.
In March 2016, 32 civilians were killed in suicide bomb attacks in Brussels.
Two explosives were detonated at Brussels airport in Zaventem and one at Maalbeek metro station in the city centre.
The attacks left more than 300 people injured.
Another bomb was found during a search of the airport.
The Islamic State of Iraq and the Levant (ISIL) claimed responsibility for the deadly attack.