As Europe's de facto capital faced an extreme security lockdown this weekend after Belgian authorities raised threat alert levels to maximum, a series of citywide safety measures were implemented to prevent a "serious and imminent" terrorist attack.

Residents were advised to stay inside, and all pedestrian activity halted - including the shutdown of public transportation, schools, and shopping centers - while authorities intensified their search for suspected ISIS militants involved in the Paris attacks.

On Sunday, authorities in Brussels launched a massive security operation during which residents were implored by Belgian officials to refrain from disseminating any information regarding the whereabouts of police and the locations of raids apparently taking place in the city via social media channels.

Police are asking the public not to report their movements on social media, please support & rt #BrusselsLockdown — Steven Vandeput (@svandeput) November 22, 2015

While many adhered to the request for silence across social media, Belgians also took a different tact to the request and began posting photos, memes, and gifs of cats and dogs with the hashtag #BrusselsLockdown. As animals of all shapes and sizes began flooding social media channels like Twitter, the hashtag quickly started trending and became viral within minutes.

Eventually, people from all over the world jumped on the hashtag, and began posting their own takes on the lockdown.

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Like the rapid social media reaction to the Paris Attacks that emerged in the form of an illustrated Eiffel Tower icon and the corresponding hashtags #JeSuiParis, #JeSuiParisien, the response, #BrusselsLockdown, points again to the immediate global communicative power of social media.