The Washington Post, external says Cherif Kouachi was introduced to radical Islam by a charismatic janitor, Farid Benyettou, who "led a band of social misfits and petty criminals through military-style training exercises in a Paris park".

Farley Katz, staff cartoonist at New Yorker Magazine: "They stood for something and they believed in it... they thought it was more valuable than themselves.

"They're quoted many times saying that they'd rather die standing than live on their knees so I think they knew that these crazy people exist and they were brave because they took that risk."

Britain's Daily Telegraph says Paris gun suspect Cherif Kouachi is a follower of Djamel Beghal, a militant with links to London's Finsbury Park mosque and who allegedly recruited the shoe bomber Richard Reid.

Beghal is said to have recruited Kouachi while he was in prison.

Thousands of Parisians have flocked to the Place de la Republique for a second night running.

Paris mayor Anne Hidalgo said: "We know that together we are much stronger than if we stay and suffer in our corner. Meeting tonight would be without doubt something that would warm the hearts of Parisians."

Image source, Getty Images

Tony Abbott, Australian Prime Minister: "We should not stop being ourselves because of this kind of attack. If we do engage in self-censorship, if we do change the way we live and the way we think, that gives terrorists a victory and the last thing that we should do is give these evil fanatics any kind of victory."

Awuku Larbi, Ghana: Many have died and continue to die all in the name of religious fanaticism and not religion itself. The truth is that true religion saves but fanaticism kills.

Jean Paul Laborde, executive director of the UN counter-terrorism directorate, says the attackers must be punished.

He says: "The attack in Paris did not only target innocent human beings, but... also constituted an unacceptable assault on freedom of expression, opinion, of the media. Impunity is not an option, those responsible for carrying out these attacks must be swiftly brought to justice."

Image source, Foreign Correspondents' Club of China

The BBC's Maria Byrne @byrnechina, external: Journalists gathered in Beijing to remember those killed in Paris #JeSuisCharlie #FCCC

Eric Denece, director of the French Centre for Intelligence Research, tells AFP that finding extremists is easy, tracking their every move is hard.

"At some point surveillance comes to an end, especially if you are smart enough to watch your step for a while. These are inevitable holes in the net," he says.

Image source, Sylvie Jullien-Para

Sylvie Jullien-Para: French and Australian people united in Martin Place, Sydney. After a minute of silence people sang La Marseillaise

"The paper will continue because they haven't won," a tearful Patrick Pelloux, Charlie Hebdo columnist, tells iTele TV.

Tony Luseno, Nairobi, Kenya: A barbaric attack indeed on people who were simply doing their jobs. We should never bow down to terrorism but instead stand resolute in defending freedom of the press.

Philippe Val, former director of the satirical magazine Charlie Hebdo, has told the BBC's Newsnight it was run by people "devoid of hate, of prejudice and was respectful of others".

Supporters of Charlie Hebdo gather outside the French embassy in Rome.

Franco Siddi, secretary general at the National Press Association of Italy, says: "Today we are here to be close to the French people, to be close to the families of the victims, close to our French colleagues and close to the victims that are not with us anymore, but for us are still here. We are here to witness the presence of freedom of speech."

In case you missed it, here is the video of Fergal Keane visiting the estate where one of the suspects, Cherif Kouachi, lived. The man's neighbour describes him as "nice, and helpful".

Booker Prize-winning author Ian McEwan has suggested that children be taught freedom of speech in schools. Writing on his website, external in the wake of the Paris attack, he argues that what he calls "murderous and self-sanctifying, radical Islam" has become a global attractor for psychopaths.

"We could really bring this right into the national curriculum in schools," he told BBC's Newsnight. "We need to be able to teach everyone just how important freedom of speech is. And how in that freedom there is mockery, satire, scholarly analysis. It's going to be difficult but talking and writing is all we've got. Slaughtering each other is going to bring us to the very gates of hell."

China's President Xi Jinping has sent a message of condolence to his French counterpart Francois Hollande.

He said China was "ready to work with France and other countries... to safeguard world peace".

"Terrorism is a common enemy of all mankind and a common threat to the entire international community," Mr Xi said in remarks reported by state news agency Xinhua.

Image source, Sabrina Chen

Sabrina Chen sent in her tribute

Charlie Hebdo's former editor Philippe Val: "Do you know what threatens democracy the most? Silence. To reduce ourselves to silence means that we will lose all we have gained of liberty, freedom for women, for homosexuals, the freedom to come and go as we please, moral freedom.

"But we must not believe that the Muslims who are today outraged by what has happened cannot understand it. They can understand it. They can understand that today, their religion needs to reform. So that it does not in the heart of the democracy where they have chosen to live, create terrorists, terrorism, which is of course opposed by most Muslims, who are victims of it."

Could the attack on Charlie Hebdo widen divisions between communities in France, asks the BBC's Fergal Keane.