Four months later, associates of those attackers killed 32 people in their home city.
Since then, attacks in France, but also in Germany, Sweden and, most recently, in Britain, have been carried out in the name of the Syria-based Islamist militant group by other young men, many of them locals, raising fears of more violence in a city where almost a quarter of the population of 1.2 million are Muslim.
Witnesses spoke of a man who shouted Islamist slogans, including "Allahu akbar" - God is greater - in Arabic, in an underground area of the station still busy with commuters making their way home and seemed to set off one or two small blasts.
Security experts said Tuesday's incident could have been similar to "lone-wolf" assaults carried out by radicalised individuals with limited access to weapons and training.
"Such isolated acts will continue in Brussels, in Paris and elsewhere. It's inevitable," Brussels security consultant Claude Moniquet, a former French agent, told broadcaster RTL.
With Islamic State under pressure in Syria - where Belgium has been the most fertile European recruiting ground for foreign Islamist fighters - he said attacks in Europe could increase, although many would be by "amateurs" doing little harm.
He compared Tuesday's incident to that on Paris' Champs-Elysees avenue a day earlier, when a man was killed when he rammed his car, filled with explosive and weapons, into a French police convoy. No one else was injured.