12 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, said sources close to the investigation.

12 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, said sources close to the investigation.

The prosecutor's office said twelve people were killed in the attack.

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 arrived at the scene of the shooting after rushing there and calling an emergency cabinet meeting, the presidency said.

The government raised its alert level to the highest possible in the greater Paris region.

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 a gunman had hijacked a car and knocked over a pedestrian while attempting to speed away.

The publication's cartoonist Renaud Luzier earlier told AFP there were "casualties" after the incident.

The satirical newspaper gained notoriety in February 2006 when it reprinted offensive cartoons of the Prophet Mohammad (PBUH) that had originally appeared in Danish daily Jyllands-Posten, causing fury across the Muslim world.