Hollande calls for 'national unity' after 12 killed in gun attack in Paris

12 people have been killed and 7 injured in Paris after three gunmen in black balaclavas burst into the offices of satirical weekly Charlie Hebdo, previously notorious for publishing satirical cartoons of the Prophet Muhammad.

The assailants’ identities have not been confirmed and are thought to still be at large in Paris, armed with kalashnikovs (AK-47s) and a rocket-launcher.

The French Interior Ministry confirmed the death toll on Wednesday afternoon, stressing that security precautions have been tightened at vital institutions and the headquarters of media organisations.

Among the dead are the cartoonists Cabu, Tignous, Charb and Wolinski (all pseudonyms used in the paper) with the original author of the cartoons satirising the Prophet Muhammad among those killed, according to French media. 10 members of the newspaper were killed, along with two police officers who had been guarding the paper's offices.

Cabu, Tignous, Charb and Wolinski, cartoonists all killed in Paris (AFP)

Witnesses have claimed that the gunmen shouted "we have avenged the Prophet" after entering the building.

Corinne "Coco" Rey, a cartoonist at Charlie Hebdo, told French newspaper L'Humanite that she and her daughter had been approached by armed gunmen at the door to the paper's building, and ordered to open the door.

"They wanted to go inside, to go upstairs," she said. "I entered the code".

"They fired on Wolinski, Cabu... It lasted five minutes... I sheltered under a desk... They spoke perfect French and claimed to be from al-Qaeda".

The gunmen reportedly shouted "Charlie Hebdo" at employees in other offices, looking for the Hebdo staff.

Video taken from a nearby building appears to show the killers escaping, apparently shouting "Allahu Akbhar".

The gunmen fled in a hijacked black four-door car, which they later abandoned in a northern Paris suburb. Police are now examining the car, whose back window has been smashed in, for any evidence.

Many other newspapers, including Le Monde and Liberation, are currently under a heavy security lockdown.

The headquarters of El Pais in Madrid, the capital of Spain, was also evacuated on Wednesday afternoon after receiving a "suspicious" package, Reuters reported.

Messages of condemnation pour in

At a press conference on the scene an hour after the attack, French President Francois Hollande said there was a need to “ensure protection in all locations".

“We have engaged the highest security level,” he told reporters. “There are also security measures that have been launched to apprehend the assailant of this attack".

He described it as “a terrorist operation...against a newspaper that has been threatened several times," denouncing it as an "attack on free speech."

He called for “national unity” and announced an emergency meeting of the French cabinet.

“Nobody can think that they can behave in France against the principle of the republic and harm the spirit of the republic,” he said. “We are in extremely difficult circumstances".

He also added that “many assassination attempts were foiled over the past few weeks.”

British Prime Minister David Cameron condemned the attack as "sickening" on Twitter.

President Obama condemned the "horrific" shooting in the "strongest possible terms".

The White House also promised to stand in "solidarity" with France, offering US help in prosecuting the attackers, who have not yet been publicly identified.

The US embassy in Paris changed its profile picture on Twitter to a picture of the hashtag #JeSuisCharlie, which has been used to express solidarity with the victims and all those affected.

Russia's President Vladimir Putin said he resolutely condemns terrorism, and expressed his condolences to the families of those killed and injured as well as to all Parisians.

World leaders and citizens alike condemned the attacks. 

Tariq Ramadan, Professor of Contemporary Islamic Studies at Oxford University, said that "contrary to what was apparently said by the killers...it is not the Prophet who was avenged - it is our religion, our values and Islamic principles that have been betrayed and tainted".

The editor-in-chief of The Daily Mash, a British satirical newspaper, expressed his shock but urged his colleagues to continue their work as normal.

Neil Rafferty said the attack was "beyond belief," saying his site is planning its response.

Though the identities of the attackers remain unknown, eye-witnesses told French news website 20minutes.fr that as they approached the building the men shouted: "Say to the media that it was al-Qaeda in Yemen" in a possible refernce to al-Qaeda in the Arabian Peninsula (AQAP), a group responsible for numerous deadly attacks in Yemen.

Charlie Winter, a researcher at anti-extremist think-tank the Quilliam Foundation, reported on Twitter that one of the men killed in Wednesday's attack, Stephane Charbonnier, had been listed as "Wanted" by AQAP's monthly magazine, Inspire.

Charlie Hebdo previously hit the headlines in 2006 after it produced an issue that featured cartoons depicting the Prophet Muhammad, which is forbidden in Islam. Outcry against the cartoons by Muslims both in France and internationally eventually led to French Interior Minister Manuel Valls banning protests agains the cartoons.

In 2011, the paper stoked more controversy by publishing a special edition entitled "Sharia Hebdo" in which the Prophet Muhammad was represented on the front cover. However, before the edition could come out, the offices of Charlie Hebdo were destroyd by an arson attack, committed at night.

Richard Malka, Charlie Hebdo's lawyer, was quoted in the Telegraph as saying its offices had been "under police protection since the Mohammed cartoon affair right up until today. Charb (the publishing director) was under special high-profile figure protection. The threats were constant. It is frightening."

Though the no-one has claimed responsibility for the attack, the media has been quick to blame Islamic militants.

The hashtag #ParisIsBurning has circulated on twitter, allegedly begun by followers of the Islamic State (IS) supporting the attack.

Charlie Hebdo’s editor-in-chief, Gerard Biard, told French media that he couldn't "understand how people can attack a newspaper. A newspaper is not a weapon of war.”

Jean-Yves Camus, a political scientist close to the paper, told Le Monde that “all the people I knew are dead, what I can tell you, is that we have never seen in the history of our country, an organ of the press being methodically wiped out in a military style operation. No newspaper has been attacked like this, because there is a principle called the freedom of the press, which up until now had been respected. This is an unimaginable escalation."

He also denied claims that Charlie Hebdo was an Islamophobic publication.

"The people who worked at Charlie Hebdo hated no-one, and certainly not the Muslims," he said. "They criticised all religions. Those who committed these murders understood nothing. This is an act of absolute hatred, the absolute denial of thought."