At least 12 people were shot dead by black-hooded gunmen at the Paris offices of a satirical weekly on Wednesday, police said.

The attack on the publication Charlie Hebdo claimed the lives of some of the best-known cartoonists in France, a judicial source said.

Editor-in-chief Stephane Charbonnier, known as Charb, and the cartoonists known as Cabu, Tignous and Wolinski were killed.