A young mother and cartoonist who survived the Charlie Hebdo massacre in Paris today said she had let the suspected Al Qaeda killers into the magazine 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 magazine building, where two masked and armed men brutally threatened us,' said Ms Rey, who draws under the name 'Coco'.

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Desperate: Corrine Rey, who's a cartoonist for Charlie Hebdo, hid underneath a desk with her daughter to escape the terrorists who killed her colleagues

Siege: The two men, who claimed to be from Al Qaeda, threatened Miss Rey into giving them the code to enter the building

Killers: One of the masked men mercilessly shot and killed a wounded police officer on the street outside

Death: 12 people, including four Charlie Hebdo journalists, were killed in the attack before the assailants fled

'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 inter-phone.

Miss 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.

She said the men 'spoke French perfectly' and 'claimed they were 'Al Qaeda terrorists'.

According to Charlie Hebdo's lawyer, four cartoonists were killed by the masked gunmen: Cabu, Wolinski, Tignous and Charb, the pen name of Stephane Charbonnier, also the chief editor at Charlie Hebdo.

Corrine's story is one of several horrifying tales from people who saw and survived the attack in Paris today.

Another eye-witness, who works in an office in the same building, told the BBC World Service: 'When I arrived at the scene it was quite disturbing as you can imagine. There were several corpses on the floor.

He arrived at the scene of the massacre just minutes after the attackers had left, and described how he tried to make some room for the wounded in the office.

Showdown: There was a fire-fight between French police and the two attackers, who claim to be from Al Qaeda, outside the building

Terrifying: Eyewitnesses say they saw the men firing indiscriminately on the street outside. This tweet allegedly shows a bullet hole from inside the Charlie Hebdo office building

Getaway: After shooting a policeman, the pair escaped in a black Citroen (pictured), which they crashed

On the run: The men, described as 'calm and highly disciplined', remain on the loose in Paris

He added: 'As we progressed through the rooms, we saw there were a lot of people down on the floor and there was blood everywhere.

'We're extremely relieved that nobody was affected by the attacks in my own office... but obviously I'm very traumatised by this attack and everything and now we're in psychological hell where we're being attended to by professionals.'

Giles Boulanger, who also works in the same building, described to French news station Itele how a colleague warned him that armed men had entered the building.

He said: 'several minutes later, we heard several shots in the building from automatic weapons from all directions.

'It was really upsetting. You'd think it was a war zone.'

The headquarters of Charlie Hebdo was attacked with a 'firebomb' in November 2011, after they put an image of the Prophet Mohammed on its cover.

Out-gunned: One eyewitness told Sky News the security presence around the building was 'useless'

Shooting: Lead cartoonist Jean 'Cabu' Cabut (pictured) was among the 12 massacred by terrorists in Paris

Security presence around the building was ineffective against the 'well trained' attackers, Stefan De Vries told Sky News.

The French journalist, who arrived at the scene moments after the attackers had fled, said: 'There was protection at the door but they killed the police officers, they executed them and they started shooting in the offices. There were more than 50 people inside.

‘It was difficult to enter but these people, the suspects were heavily armed, and shot the police so yeah, there was security but it was useless.’

Witnesses said the suspected Al Qaeda killers were heard to shout 'the Prophet has been avenged' and 'Allahu akbar!' – 'God is greatest' – 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.