Prosecutors have confirmed the suspect arrested is a French national and said they found knives, a shotgun and a gas can with an unknown liquid.
He has been identified as 39-year-old Mohamed R, a French national of North African origin and living in France.
Police in the northern Belgian city of Antwerp said the man tried to enter the main pedestrianised shopping street in a car at high speed.
Images posted on social media show investigators at the scene.
The area is still cut off by the police.
The incident comes one day after an attack in London, which also started with a driver plowing into people with a vehicle and killed four people.