Three masked attackers brandishing Kalashnikovs burst into the Charlie Hebdo headquarters, opening fire on staff after seeking out journalists by name.

Those executed included four of the most famous cartoonists in France – men who had regularly satirised Islam and the Prophet Mohammed – including the newspaper’s editor-in-chief, Stephane Charbonnier.

Witnesses said the suspect Al Qaeda killers were heard to shout ‘the Prophet has been avenged’ and ‘Allahu akbar!’ as they stalked the building.

Horrific footage also emerged showing an injured police officer slumped on the pavement outside the office as two of the gunmen approach.

In an apparent desperate plea for his life, the officer is seen slowly raising his hand towards one of the attackers, who responds by callously shooting him in the head at point-blank range. 

Despite a shoot-out with armed officers, the ‘calm and highly disciplined’ men who reportedly spoke perfect French were able to escape in a hijacked car and remain on the loose. 

Brutal execution: A police officer pleads for mercy on the pavement in Paris before being shot in the head by masked gunmen during an attack on the headquarters of the French satirical publication Charlie Hebdo, a notoriously anti-Islamic publication

Gunned down in cold blood: Horrific footage shows the injured police officer slumped on the pavement as two of the gunmen approach. In a desperate plea for his life, the officer slowly raises his hand towards one of the attackers, who callously shoots him at point-blank range

‘Massacre’: The gunmen are seen brandishing Kalashnikovs as they move in on the injured police officer from their vehicle outside the office

Police officers and firefighters gather in front of the offices of Charlie Hebdo in Paris today after gunmen stormed the building, Firefighters carry an injured man on a stretcher in front of the offices of French satirical paper Charlie Hebdo after the shooting

By midday, there were reports of up to 12 people dead and 10 wounded, four critically, including journalists, administrative staff, and police officers who attended the scene. 

President Francois Hollande described the bloodbath as a ‘barbaric attack against France and against journalists’ and vowed to hunt down those responsible.

As well as the AK47 assault rifles, there were also reports of a rocket-propelled grenade being used in the attack, which took place during the publication’s weekly editorial meeting, meaning all the journalists would have been present.

They are said to have sought out staff ‘by name’, according to a police source, adding that Charbonnier, known as Charb, a cartoonist responsible for an anti-Islam front page, was among those killed. 

Mr Charbonnier was included in a 2013 Wanted Dead or Alive for Crimes Against Islam article published by Inspire, the terrorist propaganda magazine published by Al Qaeda. 

Cartoonists Cabu, Tignous and Wolinski were all also reported dead.  

A young mother and cartoonist who survived the massacre today told how she had let the suspected Al Qaeda killers into the office.

Corrine Rey said she had returned from picking up her young daughter from a kindergarten when she was confronted by two heavily armed men wearing balaclavas.

‘I had gone to pick up my daughter at day care, arriving in front of the building, where two masked and armed men brutally threatened us,’ said Ms Rey, who draws under the name ‘Coco’.

‘They said they wanted to go up to the offices, so I tapped in the code,’ said Ms Rey, referring to the digi-code security system on the interphone.

Ms Rey and her daughter hid under a desk, from where they saw two other cartoonists being executed. ‘They shot Wolinski and Cabu,’ she said. ‘It lasted five minutes. I had taken refuge under a desk.’

Ms Rey said the men ‘spoke French perfectly’ and ‘claimed they were ‘Al Qaeda terrorists’. 

Gunmen reportedly told another witness: ‘You say to the media, it was Al Qaeda in Yemen.’ 

Meanwhile, there were reports of a car explosion outside a synagogue in Sarcelles, a commune in the northern suburbs of Paris, just hours after the Charlie Hebdo attack. 

He said: ‘There were very many people in the building. We evacuated via the roof just next to the office. After around ten minutes we saw two heavily armed, masked men in the street’.

Another witness said: ‘There was a loud gunfire and at least one explosion. When police arrived there was a mass shoot-out. The men got away by car, stealing a car.’

A police official, Luc Poignant, said: ‘It’s carnage.’

The latest tweet published by the newspaper’s official Twitter account featured a cartoon of Abu Baghdadi, the leader of Islamic State.

After the shooting, hundreds of comments were posted on the Charlie Hebdo Twitter page, with one user, David Rault, writing: ‘A sad day for freedom of expression.’ 

Charlie Hebdo’s editor-in-chief Gerard Biard escaped the carnage because he was in London.

He told France Inter: ‘I am shocked that people can have attacked a newspaper in France, a secular republic. I don’t understand it.

‘I don’t understand how people can attack a newspaper with heavy weapons. A newspaper is not a weapon of war.’

Mr Biard said he did not believe the attack was linked to the newspaper’s latest front page, which featured novelist Michel Houellebecq, who has previously sparked controversy with comments about Islam.

And he said the newspaper had not received threats of violence: ‘Not to my knowledge, and I don’t think anyone had received them as individuals, because they would have talked about it. There was no particular tension at the moment.’

A visibly shocked French President François Hollande, speaking live near the scene of the shooting, said: ‘France is today in shock, in front of a terrorist attack.

‘This newspaper was threatened several rimes in the past and we need to show we are a united country.

‘We have to be firm, and we have to be stand strong with the international community in the coming days and weeks.

‘We are at a very difficult moment following several terrorist attacks. We are threated because we are a country of freedom

‘We will punish the attackers. We will look for the people responsible.’ 

Prime Minister David Cameron joined the condemnation of the attack, saying: ‘The murders in Paris are sickening. 

‘We stand with the French people in the fight against terror and defending the freedom of the press.’

The British Foreign Office immediately updated is advice for travellers heading to Pairs, warning: ‘There is a high threat from terrorism.’

It added: ‘If you’re in Paris or the Ile de France area take extra care and follow advice of French authorities.’  

Luce Lapin and Laurent Leger, who have both worked at Charlie Hebdo, were using Twitter hours before the attack, with the most recent tweet posted by Lapin praising cartoonist Cabu.

It read: ‘Cabu, a great man! And honest, he doesn’t eat foie gras.’ 

While Leger’s made a political point about taxes. 

It said: ‘Macron [French ministry of economy] wants more billionaires in France, the same that use tricks for not paying ISF [solidarity tax on wealth].’ 

A source close to the investigation said men ‘armed with a Kalashnikov and a rocket-launcher’ stormed the building in central Paris and ‘fire was exchanged with security forces.’

The offices of the same newspaper were burnt down in a petrol attack in 2011 after running a magazine cover of the Prophet Mohammed as a cartoon character.

At the time, the editor-in-chief, Stephane Charbonnier, said Islam could not be excluded from freedom of the press.

He said: ‘If we can poke fun at everything in France, if we can talk about anything in France apart from Islam or the consequences of Islamism, that is annoying.’ 

Mr Charbonnier, also known as Charb, said he did not see the attack on the newspaper as the work of French Muslims, but of what he called ‘idiot extremists’.

The cover showed Mohammed saying: ‘100 lashes if you are not dying of laughter’.

This week’s Charlie Hebdo also featured the author Houellebecq, whose new novel imagines Muslims tkaing over the French government in 2022. 

Inside, there was an editorial, attributed to the Prophet Muhammad, and more cartoons – one showing the Prophet with a clown’s red nose. 

Depiction of the Prophet is strictly prohibited in Islam, but the newspaper denied it was trying to be provocative.

A firebomb attack gutted the headquarters of Charlie Hebdo in November 2011 after it put an image of the Prophet Mohammed on its cover.

Charlie Hebdo has become a byword for offensive statements in France after taking several highly provocative swipes at Islam.

The newspaper once named Prophet Mohammed as its guest editor, published cartoons of the holy figure in the nude, and once renamed itself Sharia Hebdo with the cover slogan ‘100 lashes if you don’t die of laughter’.

The controversy began in 2006 when the publication reprinted now-infamous cartoons of Prophet Mohammed by Danish artist Kurt Westergaard.

When the images originally appeared they lead to days of protests across the Middle East and in Western cities. The decision to reprint the images landed the then-editor in court under anti-terror laws, though he was later acquitted.

The Hebdo offices were burned to the ground in 2011 when attackers used Molotov cocktails to start a blaze early in the morning of November 2.

There was nobody in the building at the time, and the target was instead thought to be the newspaper’s computer system, which was completely destroyed.

Riot police were forced to stand guard outside the building for days following the attack, as the editors took a defiant stance, choosing to reprint the cartoon images multiple times.

In 2012 they again printed cartoons of the Prophet Mohammed as a deliberately provocative gesture while violent protests were taking place across the Middle East.

The following year the newspaper’s office again had to be surrounded by riot officers after they published a cartoon booklet depicting the Prohpet naked as a baby and being pushed in a wheelchair.

On the final page of the booklet there was a note from the editor, Stephane Charbonnier, saying the images were ‘halal’ because Muslims had worked on them, and that they were factually accurate as they had been derived from descriptions in the Koran.

The satirical publication, widely seen as France’s answer to Private Eye, prides itself on a mixture of tongue-in-cheek reporting and investigative journalism. 

Hebdo’s current office building has no notices on the door to prevent a repeat of the attacks that have occurred in the past.

In an interview with De Volkskrant in January 2013, Mr Charbonnier revealed he had been placed under constant police protection for four months after one of the cartoon issues was published.

He shrugged off criticism that he was only publishing the images to gain notoriety for Hebdo, and insisted that he was instead defending the right to free speech.

Mr Charbonnier pointed out that the newspaper had poked fun at feminism, nuclear energy and homeland security, but the Islam issues always attracted the most publicity.