PARIS - At least 10 people were killed when gunmen armed with Kalashnikovs and a rocket-launcher opened fire in the offices of French satirical weekly Charlie Hebdo on Wednesday, Paris prosecutors said.
"At this stage" ten people are dead, said the prosecutor's office, without detailing how many had been injured.
Deputy Mayor of Paris Bruno Julliard earlier said "six people are seriously injured", including a policeman.
It was not clear whether these now figured among the dead.
French President Francois Hollande was on his way to the scene of the shooting and called an emergency cabinet meeting, the presidency said.
A source close to the investigation said two men "armed with a Kalashnikov and a rocket-launcher" stormed the building in central Paris and "fire was exchanged with security forces."
The source said gunmen had hijacked a car and knocked over a pedestrian as he sped away. The publication's cartoonist Renaud Luzier earlier told AFP there were "casualties" after the incident.
The satirical magazine gained notoriety in February 2006 when it reprinted cartoons of the Prophet Mohammed that had originally appeared in Danish daily Jyllands-Posten, causing fury across the Muslim world.
Its offices were fire-bombed in November 2011 when it published a cartoon of Mohammed and under the title "Charia Hebdo".
Despite being taken to court under anti-racism laws, the magazine continued to publish controversial cartoons of the Muslim prophet.
In September 2012 Charlie Hebdo published cartoons of a naked Mohammed as violent protests were taking place in several countries over a low-budget film, titled "Innocence of Muslims", which was made in the United States and insulted the prophet.
French schools, consulates and cultural centres in 20 Muslim countries were briefly closed along with embassies for fear of retaliatory attacks.
Editor Stephane Charbonnier has received death threats and lives under police protection.