"It is a criminal act," a local official told AFP, adding that a police investigation has been opened. No link was suggested with the deadly attack on Paris magazine Charlie Hebdo a day earlier, which killed 12 people.
President Francois Hollande called the massacre in Paris-- thought to be the worst attack on French soil since 1961 -- "an act of exceptional barbarity" and "undoubtedly a terrorist attack".
In the hunt for the attackers, police published pictures of the wanted men in an urgent appeal for information as a manhunt stretched long into the night with a raid by elite anti-terror police in the northern city of Reims.
The magazine’s office was burned 3 years ago in response to its publication of cartoons of the Prophet Muhammed (PBUH).
In November 2011, Charlie Hebdo’s offices caught fire the day it was due to publish a cover making fun of Islamic law.