Gunmen approach a wounded police officer (R) on the ground at point-blank range, outside the offices of French satirical newspaper Charlie Hebdo in Paris. Image Credit: Reuters

Paris: At least 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, French police have said.

President Francois Hollande headed to the scene of the attack and the government said it was raising France's security level to the highest notch.

"This is a terrorist attack, there is no doubt about it," Hollande told reporters.

Another 10 people were injured in the incident and police union official Rocco Contento described the scene inside the offices as "carnage".

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 Mohammad (PBUH) 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 Prophet Mohammad and under the title "Charia Hebdo".

Despite being taken to court under anti-racism laws, the magazine continued to publish controversial cartoons of the Prophet.

A video uploaded to YouTube showing the suspected attackers engaging French police in a firefight in Paris before boarding a black getaway car:

In September 2012 Charlie Hebdo published controversial cartoons of Prophet Mohammad 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, four cartoonists killed

Editor Stephane Charbonnier had received death threats and lived under police protection before the attackers killed him, along with four cartoonists, inside the weekly's office in the Wednesday attack, according to media reports.

A video showing the street near the office at which the shooting took place, posted to YouTube by France 24.