The offices of Charlie Hebdo, the weekly French satirical magazine, were firebombed early Wednesday morning.
It comes a day after the publication named the Prophet Muhammad as its "editor-in-chief" for its next issue.
The cover of the magazine carried a caricature of the Prophet making a facetious comment.
French Prime Minister Francois Fillon has described the petrol-bombing as an unjustifable attack on the freedom of the press.
The editor-in-chief of the magazine, Stephane Charbonnier, said Islam could not be excluded from freedom of the press.
He said: "If we can poke fun at everything in France, if we can talk about anything in France apart from Islam or the consequences of Islamism, that is annoying."
Mr Charbonnier, also known as Charb, said he did not see the attack on the magazine as the work of French Muslims, but of what he called "idiot extremists".
The magazine has a reputation for extreme satire, following the strong tradition of comic strips and caricatures in France. Describing its content, the BBC says that "Over the years, it has printed examples which make today's representations of Muhammad look like illustrations from a children's book. ... So today when the paper's staff say there is nothing unusually provocative about the Charia Hebdo issue - with its front-page cartoon of 'guest-editor' Muhammad -- they are being perfectly truthful."
Video below (in French) via Inconvox.com: (courtesy of Mike Lynch Cartoons)