One of the most retweeted images following Tuesday's attacks in Brussels came from Jean Plantereau. Known at Plantu, he is one of France's most political caricaturists and illustrates for French daily "Le Monde."

With the November 13 attacks in Paris still fresh in the public's minds, Plantu struck a nerve by expressing not just France's solidarity with Belgium in light of the tragedy, but the two countries' shared grief.

As news of the tragedy broke, "Le Monde" drew on illustration as well, posting an image of Belgian comic figure Tintin, created by cartoonist Hergé. In publication from 1929 to 1976, Tintin was one of the most popular and widely read comic figures of the 20th century, which is why Belgium has become an emblem of the genre.

The tweet reads: "Explosions in Brussels: The country of comics is grieving."

In a tribute to Tintin, Danish illustrator Soren Juhl offered this moving contribution, proclaiming #Loveforall.

"The expression I gave Tintin is the same expression I had on my face," Juhl told DW in an interview.

Similar to the reaction following the November Paris attacks, the hashtag #JeSuisBruxelles (I am Brussels) quickly began trending.

Spanish soccer player Pedro Rodriguez, who plays for FC Chelsea, was one of many to tweet this heart marked with Belgium's national colors.

Other celebrities and sports stars joined in the solidarity with similar messages, including Marc Márquez, a Spanish Grand Prix motorcycle road racer and former MotoGP world champion.

Meanwhile, the Manneken Pis, a landmark in Brussels, was a popular motif when it came to expressing anger, spite and frustration toward the terrorists responsible for Tuesday's attacks. The 61-centimeter statue, depicting a young boy urinating into a fountain, has been on display in the Belgian capital for nearly 400 years.

The French news cartoonist Nawak drew on this symbol in his cartoon with the caption, "Here's a present from Belgium - Support to our Belgian friends."

"I wanted to bring a touch of humor to this horrible day," Nawak told DW. Cartoons are "a way of exorcizing fear, the choc, and of showing our support," he added.

The Mazel Galerie, located in downtown Brussels and run by a French family, posted the following tweet.

Manuel Jous, journalist for the Belgian public broadcasting service RTBF, was among the many people who posted this other picture featuring the Manneken Pis.

To join the expressions of solidarity on Twitter, follow the hashtag #JeSuisBruxelles.