However, the images posted were not of the deserted city streets with police cordons, but of cats. The hilarious response demonstrated the good humour of the Belgium people even in times of crisis, as they endeavoured, in the most imaginative way possible, to support the police services.
The images of cute kittens countered the images of violence and gunman that usually accompany anti-terror raids. Commentators acknowledged the witty response. "#Catstorm on #BrusselsLockdown = the best of human nature responding to the worst of human nature. Hope all are safe," wrote one Twitter user poignantly.
"Tbf the very possible idea of angry, confused terrorists scrolling through the#BrusselsLockdownhashtag is making me quite happy right now," wrote another.
While the capital remains in lockdown for three days as police search for fugitive Salah Abdeslam, a key conspirator in the Paris attacks, the ingenuity, the solidarity and the good humour of the cat loving people of Belgium, gives us a reason to smile, even in the face of terror.