Journalists and other staff at Germany's international broadcaster Deutsche Welle (DW) on Thursday paid tribute to the 12 people killed during the attack on the offices of French satirical magazine Charlie Hebdo.

Scores of people gathered outside the broadcasting center in Bonn, Germany, holding up signs reading "Je suis Charlie" ("I am Charlie"), in support of the French magazine and press freedom.

Altogether twelve people were killed on Wednesday when two masked gunment raided the offices of the magazine in the capital, Paris, during an editorial meeting. Eight journalists, including the editor, two policemen, a maintenance worker and a visitor were among the dead.

Police are hunting for two brothers, Cherif and Said Kouachi, whom they suspect of having carried out the attack. Both are known to anti-terror police. Seven people with links to the brothers have been detained for questioning.

The attack has prompted an outpouring of similar expressions of solidarity around the world. People from Russia to the United States have rallied in their tens of thousands, calling for press freedom to be protected.

France has declared Thursday as a national day of mourning.