
As darkness fell across Europe, tens of thousands took to the streets to show their solidarity with those killed by gunmen at the offices of satirical French weekly Charlie Hebdo.

The scenes were replicated across France, in London and around the world with crowds holding placards bearing the slogan #JeSuisCharlie, which means ‘I am Charlie’ in French. Others were seen carrying enlarged versions of the some of the newspaper's anti-Islamist cartoons.

Meanwhile the website of French newspaper Le Monde last night showed an interactive map of vigils being held across the world in Dublin, Edinburgh, Amsterdam, Brussels, Madrid, Rome, Berlin, Vienna, Moscow, and as far afield as Tunis, Lima, Rio de Janeiro and Madagascar.

In London, hundreds of people filled Trafalgar Square at a silent vigil for those killed when masked gunmen stormed the newspaper's headquarters. Many held pens, pencils and notebooks in the air to show their support for the journalists, cartoonists and police officers who lost their lives.

The gatherings were held as French President Francoise Hollande declared tomorrow a day of national mourning tomorrow in respect for the victims of this morning's attack.

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Unity: Protesters hold up their phones at a vigil held in Toulouse. Francoise Hollande has declared tomorrow a day of national mourning

Touching: The steps of a public building in Lyon are lit with candles as thousands of people gather to show support for Charlie Hebdo

Basic right: Standing in support of the freedom of the press, these protesters hold an illuminated sign at a gathering in the centre of Paris

London: The mood was sombre in Trafalgar Square as protesters with posters reading 'Je Suis Charlie' showed their solidarity with France

Tribute: Outside the EU headquarters in Brussels, Belgium, protesters held paper lanterns as they met to remember those who have died

Barcelona: In a sign of support of the journalists who lost their lives yesterday, protesters held pens, pencils and notebooks in the air

Unity: Tens of thousands of people last night joined peaceful rallies in support of the people killed at the massacre in central Paris

At the Place de la Republique, in central Paris, less than half a mile from the Charlie Hebdo offices, protesters stood shoulder to shoulder, proudly holding 'Je Suis Charlie' signs above their heads.

In central London, the mood was sombre as a large crowd gathered in front of The National Gallery, to express a mute horror at the events in the French capital. Dozens of French people were among them, along with those of other nationalities who came to show they would not bow to terrorism.

Vigils were held into the night across France, including gatherings in Marseille, Nice and Rennes – with more than 10,000 people congregating to mourn in both Toulouse and Lyon.

And in a show of support for the European neighbours, Germans gathered outside the French embassies in Berlin and Madrid last night - signs illuminated by candlelight.

The crowds were gathered in support of 12 people - including four of France's most revered cartoonists - who were executed by masked attackers, brandishing Kalashnikovs, who burst into the Charlie Hebdo headquarters, opening fire on staff after seeking out journalists by name.

Witnesses said the suspected Al Qaeda gunmen were heard to shout 'the Prophet has been avenged' and 'Allahu akbar!' – Arabic for 'God is great' – as they stalked the building.

They headed straight for the paper's editor and cartoonist, Stephane Charbonnier, killing him and his police bodyguard. The security had been recruited to protect him after extremists firebombed the offices in 2011 over a satirical cartoon about the Prophet Mohammed.

A year later, Mr Charbonnier famously dismissed threats against his life, declaring: 'I would rather die standing than live kneeling.'

The militants also killed three other renowned cartoonists – men who had regularly satirised Islam – and the newspaper's deputy chief editor.

People gather round candles and pens that have been assembled as a makeshift shrine at the Place de la Republique in Paris last night

Pride: In the Place de la Republique in Paris, some of those gathered proudly carried the Tricolor - the country's national flag

Support: Crowds of people carrying 'Je Suis Charlie' placards met in the centre of Nice, in the south of France, in a show of solidarity

Defiance: In a show of solidarity for their European neighbours, this group of protesters met outside the French embassy in Berlin last night

'Je Suis Charlie': Many of the protesters have adopted the slogan 'I am Charlie' in a show of support for the murdered Charlie Hebdo journalists

Peaceful: Hundreds have started to gather in the Place de la Republique in the centre of the capital. Similar meetings are being held in Rennes

Peaceful: Hundreds have started to gather in the Place de la Republique in the centre of the capital. Similar meetings are being held in Rennes

Protesters in Trafalgar Square, London, held up pens and notebooks in a show of support for the journalists who lost their lives

Respect: Hundreds of people stood in silence in Nice on Wednesday night - a moving tribute to those who lost their lives yesterday

The phrase #JeSuisCharlie had become a rallying call within minutes of yesterday’s attack on the office of Charlie Hebdo.

By late afternoon it had been tweeted more than 250,000 times by people showing their unity with the satirical magazine and the victims.

The Archbishop of Canterbury Justin Welby tweeted the hashtag and wrote in French: ‘The response to such demonic violence is love for those who suffer and virtuous action against evil’, followed by the same tweet in English.

Twitter users wrote poignant outpourings of grief alongside the #JeSuisCharlie hashtag last night.

The US embassy in France was one of those which changed its official Twitter profile, @USEmbassyFrance, to show the #JeSuisCharlie logo as its picture.

Meanwhile the French news agency AFP tweeted a photograph of its dozens of staff holding placards, and held a minute’s silence for their fellow journalists.

Google France paid tribute to the Charlie Hebdo victims by posting an image of a black ribbon below its search box, and the #JeSuisCharlie hashtag was also shared by tens of thousands of people across the image-sharing website Instagram.

A Facebook group called Je Suis Charlie was set up to inform people of vigils throughout the world – which it described as ‘good gatherings of peace-lovers’ – and had attracted more than 80,000 members within hours of forming.

Charlie Hebdo’s website crashed last night and when it returned online simply showed a black screen with the words ‘Je Suis Charlie’ in white, followed by a link to a seven-page document with ‘Je Suis Charlie’ written on each page in seven languages, including Arabic, German and Spanish.

Slogan: 'Je Suis Charlie' posters were held by many in Nice. Others waved banners with slogans such as 'Press freedom has no price'

Close: This gathering took place in the Place de la Republique in Paris - less than half a mile from where the massacre took place yesterday

Response: Masked attackers brandishing Kalashnikovs burst into the Charlie Hebdo headquarters, last night people gathered in support

People paid tribute to those who died yesterday by organising peaceful rallies in Paris, other French cities and overseas

People gathered in support as journalists around the world led the trend for the hashtag, which translates as 'I am Charlie'

The attack not only targeted the lives of innocent people, but also the freedom of the press, said Professor Anthony Glees, Director, Centre for Security and Intelligence Studies (BUCSIS) at the University of Buckingham.

It was this freedom, one of the core values of all Western democracies that is also being supported by those gathered in streets and squares across Europe.

Some waved banners with slogans such as 'Press freedom has no price' and 'Charb mort libre' (Charb died free), a reference to the newspaper's slain editor-in-chief Stephane Charbonnier.

Others wore black stickers marked 'Je suis Charlie' (I am Charlie), a slogan aimed at showing solidarity with the victims of the deadliest attack in France in decades.

'It's terrible that these people were murdered. In future, no-one will be able to speak his mind. We have to demonstrate in our thousands,' said Beatrice Cano, a demonstrator in her fifties, who was carrying the latest issue of Charlie Hebdo.

A protester in Trafalgar Square, Dean Stoker, a 38-year-old architect from London, said: 'I am just here out of solidarity. I was really sickened by what I saw today. It is an incredibly important thing, freedom of the press and tolerance of others.'

The mood was sombre in Trafalgar Square, central London, as hundreds gathered in a show of solidarity with those murdered yesterday

People look on at Charlie Hebdo written in candles at Old Port of Marseille (left) and flowers are left outside the French consulate in Istanbul

Thousands of people in the centre of Lyon for a moment of silence as they pay their respects to the victims on the deadly attacks in Paris

Members of the European Parliament, above, were among those who took to the streets of Brussels to pay tribute of yesterday's attack

Candles and cards with 'Je Suis Charlie' create a makeshift shrine in a corner of the Place de la Republique in Paris

Hundreds of candles line the steps of a public building in Lyon, France, where people have gathered to mark the tragedy

People gather at the French consulate in Barcelona. The image of a pen clutched defiantly in a fist has become another symbol of the protest

In America: Mourners gather during a rally in support of Charlie Hebdo, a French satirical weekly newspaper that fell victim to an terrorist attack, Wednesday, January 7, 2015, at Union Square in New York

Windows to departed souls: At the Union Square, New York protest, mourners help up signs depicting the eyes of the Charlie Hebdo victims

Their hears are with the French: A New Yorker holds up a heart reading Je Suis Charlie, with the designs of both the French and American flags

In Brazil: A group of two men and two women hold up 'I am Charlie' signs in a plaza in Rio de Janeiro, Brazil on Wednesday following the horrendous attach

Young and old: Children join the vigils to mourn the victims of the Charlie Hebdo shooting in Sao Paulo, Brazil Wednesday night

In Canada: Bruno Clerc, Consul General of France Montreal Mayor Denis Coderre and Quebec Transport Minister Robert Poeti, front row left to right, lead dignitaries in the signing of the French national anthem during a vigil in front of Montreal City Hall on Wednesday

Love from California: Tea lights spell out 'Je suis Charlie' at a gathering to mourn the slain newspaper staff in San Francisco, California

Mourners hold up the Je Suis Charlie signs at a gathering near San Francisco's Union Square

Alice Blanc, 19, a law and development student studying in London but originally from Paris, held up a quote often attributed to Voltaire, saying: 'I do no agree with what you have to say, but I will defend to death your right to say it.'

She said: 'I don't think a country like France today should have a problem with freedom of speech.

'No matter what a journalist or magazine has to say, even if it is not what the majority of people think, they still have the right to say it without feeling in danger, which is the case today.'

Esther Benjoar, 25, a Parisian who has lived in London for the last two years, said: 'It is people like you and I who went to work today who got killed for their passion, their job.

'It is the right that the French republic gave them to say what they want to say, and they got killed because of that. They didn't do anything wrong and I think it is time for France to fight against terrorism.'

After more than half an hour of quiet vigil, a woman's French voice pierced the silence. She shouted: 'Freedom of the press! Freedom of speech!'

A woman lights a candle during a gathering at the Place de la Republique, another example of the peaceful protests being held last night

London: Crowds also gathered outside the National Gallery in Trafalgar Square in a show of support of those murdered in Paris yesterday

Madrid: People holding makeshift banners reading Je Suis Charlie gathered outside the French embassy in Madrid, in another organised rally

Geneva: Candles and a Je Suis Charlie mark another peaceful protest organised in solidarity. This one took place in Switzerland

The protests were held as French President Francoise Hollande (pictured last night) declared tomorrow a national day of mourning

This afternoon, horrific footage of the attack emerged showing an injured police officer slumped on the pavement as two gunmen approached him outside the office minutes later.

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 were able to escape in a hijacked car and remain on the loose.

The attack on Wednesday comes after a series of strikes on shoppers in French cities in the lead up to Christmas.

Throughout the day, thousands of Twitter users have been expressing their solidarity with the news magazine with the hashtag #JeSuisCharlie after the attack at their offices this morning.

Journalists around the world led the trend for the hashtag, which translates as 'I am Charlie', as events following the massacre unfolded this afternoon.

People light candles on this wet pavement outside the French embassy in Stockholm, Sweden, in tribute to the French massacre

Hundreds of tea lights in glass holders create a moving shrine in Lyon. Tomorrow, the whole country will mourn those who lost their lives

Pens and pencils are held up by demonstrators in Trafalgar Square, London - a simple way to remember the journalists who died

A young boy is among those lighting a candle under large mirrored panels at an outdoor gathering in Marseille, southern France

After London, the protest spread to other parts of the UK, with this group of people, carrying Je Suis Charlie signs, meeting in Bristol

By 4.15pm, nearly five hours after three gunmen stormed the building and opened fire in the Charlie Hebdo newsroom, it had already been tweeted more than 250,000 times, according to one social analytics website.

#JeSuisCharlie began trending worldwide about an hour after news of the attack broke, with users expressing sympathy for the victims and support for free speech.

Many of the tweets included satirical cartoons, including one published in 2012 by New Yorker magazine of a blank square with the message: 'Please enjoy this culturally, ethnically, religiously and politically correct cartoon responsibly. Thank you'.

Another tweet under the hashtag by David Pope, political cartoonist at The Canberra Times in Australia, included a cartoon showed a masked gunman standing next to the corpse of a cartoonist. A speech bubble says: 'He drew first.'

Among the first to use the hashtag was Thierry Puget, who made the graphic at the top of this story, which has been widely retweeted by others expressing solidarity with the magazine.

Others posted images of Charlie Hebdo's most famous and controversial front covers of recent years, including one of an issue supposedly guest-edited by the Prophet Muhammad promising 'a hundred lashes if you don't die laughing.'

Assault: The attack in Paris follows pre-Christmas attacks on hoppers in various parts of France. Above, protesters in Toulouse last night

Social movement: Je Suis Charlie, a slogan that was first shared on Twitter this afternoon, was adopted by protesters in Nice (left) and Paris

Standing in front of a large Christmas tree in the city centre, protesters gather in Strasbourg, eastern France to show their support

Two young girls hold a banner reading Je Suis Charlie - I am Charlie - between them as they join hundreds of people in Marseille, France

A boy adds his hand-written Je Suis Charlie note to a makeshift shrine that has been set up near the EU headquarters in Brussels

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.

Speaking to MailOnline, Professor Glees said it was not yet clear whether the killings were in an act of retaliation for a recently tweeted cartoon mocking Islamic State leader Dr Al-Baghdadi, or for the publication of a tasteless cartoon of the Prophet Muhammad in 2011.

Crowds gathered on the streets of Geneva, Switzerland, with some protesters holding copies of Charlie Hebdo and others carrying signs

The 'Je Suis Charlie' slogan is given a Spanish translation - Yo Soy Charlie - on this shrine near the EU headquarters in Brussels

People walk past flowers that have been laid in tribute to victims of the attack in front of the French Embassy in Copenhagen, Denmark

People pack into the centre of Marseille, in southern France, to remember those who have lost their lives in the attack

Hundreds gather in front of Club de la Presse - the press club - in Montpellier, southern France, as darkness falls

Two women hold candles at a rally in the Place de la Republique in Paris (left) and more candles are lit by protesters in Geneva (right)

He said: 'The three terrorists were apparently heard after the bloodbath shrieking 'we have avenged the Prophet' but whether they were directly linked to Al-Qaeda, to the IS or an Al-Qaeda franchise in Yemen remains to be seen.'

He also critisised the French police for not better protecting the cartoonist and his office, despite the threats he had received following the publication of the cartoon.

He said: 'What is not in doubt is that the French state, and above all the French president, have failed to protect the people of France and we are all the worse off for that.

'Only two policemen guarded Charlie Hebdo's offices, despite the now dead editor, Stephane Charbonnier, being under police protection and despite the magazine now being a sitting duck target. Two policemen? There should have been two hundred.'

He added that David Cameron was right to say that Britain is 'sickened' by the murders and that we stand with the French people in the fight against terror and in defense of the freedom of the press.

He said: 'When we see journalists slain to stop them publishing perfectly lawful material we should indeed come and defend the freedom of the press because it is a vital democratic freedom.

'Let's hope David Cameron remembers his own words when the time comes to debate yet again Lord Leveson's plans to curb that freedom.'