PARIS — Twelve people were killed today at the Paris headquarters of satirical weekly Charlie Hebdo.

Authorities claim at least two gunmen armed with assault rifles attacked the magazine’s offices, while the editorial team was having its weekly meeting. Victims include Jean Cabut, aka Cabu, and Stéphane Charbonnier, aka Charb, two of France’s best-known and most talented comic strip artists and caricaturists. Charbonnier was also publisher of the magazine.

The gunmen have escaped and are now on the run.

French President Francois Hollande visited the crime scene and described the shooting as an “terrorist attack,” and “an exceptional act of barbarism committed against a newspaper.”

U.K. Prime Minister David Cameron reacted with a tweet saying, “We stand united with the French people in our opposition to all forms of terrorism & stand squarely for free speech and democracy.”

A fierce advocate for free speech, Charlie Hebdo was founded in 1969 and is known for its satirical, and often controversial, cartoons.

In 2006, it sparked a large controversy following the publication of 12 caricatures of Prophet Muhammad. Then in 2011, the magazine was fire-bombed after publishing a special issue titled Charia Hebdo with a caricature of Prophet Muhammad on the cover. Two years later, Charlie Hebdo published a comic book biography of Islam’s founder.

The magazine’s most recent tweet displayed a cartoon of Abu Bakr al-Baghdadi, the Islamic State’s driving force. This week’s issue features a caricature of Michel Houellebecq, a well-known writer whose latest book, “Soumission” (“Submission”) – deemed anti-Islam by many — depicts an imaginary political party called Muslim Fraternity ruling over France.

Some eyewitnesses said several men carrying Kalashnikovs took part in the massacre and shouted “Allaou Akbar.”

French TV channels interrupted their programing and sent reporters on the ground to provide nonstop coverage.

This attack is reportedly the deadliest one perpetrated in France since 1835.  Mass shootings are rare in France, which boasts strict gun control laws.

It’s not the first time, however, that a print publication has been attacked. In 2013, Liberation, a left-wing national newspaper, was attacked by a lone gunman who critically-injured one person. The suspect, Abdelhakim Dekhar, who was arrested later that year, is also accused of threatening a senior editor at news channel BFMTV.

The Charlie Hebdo carnage will likely fuel the racism and anti-Islam sentiment which has been on the rise in France.  It will also certainly boost the popularity of far-right (Front national) party leader Marine Le Pen, who is expected to run for President in 2017.

Update: President Obama has issued a statement on the attack: “I strongly condemn the horrific shooting at the offices of Charlie Hebdo magazine in Paris that has reportedly killed 12 people. Our thoughts and prayers are with the victims of this terrorist attack and the people of France at this difficult time. France is America’s oldest ally, and has stood shoulder to shoulder with the United States in the fight against terrorists who threaten our shared security and the world. Time and again, the French people have stood up for the universal values that generations of our people have defended. France, and the great city of Paris where this outrageous attack took place, offer the world a timeless example that will endure well beyond the hateful vision of these killers. We are in touch with French officials and I have directed my Administration to provide any assistance needed to help bring these terrorists to justice.”

Ronald A. Lindsay, president and CEO of the Center for Inquiry, a nonprofit org based in New York, also spoke out against the terrorist act: “We are heartbroken by the unthinkable and cowardly attack at the magazine Charlie Hebdo in Paris today, and outraged that such a barbaric act was a response to journalists and satirists exercising their right to free expression. As publishers of Free Inquiry, the first (and for some time, the only) U.S. publication willing to publish the cartoons of Muhammad that sparked riots in 2005 after they appeared in the Danish newspaper Jyllands-Posten, we stand in resolute solidarity with the people of Charlie Hebdo, and all those writers, thinkers, and satirists who know that no idea or individual ought to be immune from criticism, and have the courage to point out the flaws and fallacies of even the most deeply-held beliefs.”

In a show of solidarity with Charlie Hebdo, Linday also pledged to “prominently display on our website the cartoon of ISIS leader Abu Bakr al-Baghdadi that apparently was one of the motivations for the attack. We will not be cowed by the savagery of those few who would like to see the world dragged back to the Dark Ages, who will kill to protect their backward ideologies from criticism, and we will continue to fight for the right of all people to dissent, to satirize, and to freely speak their minds.”

A demonstration has been organized in Paris this evening in order to pay homage to the victims and show solidarity towards Charlie Hebdo. The French guild of authors, directors and producers (ARP) will join the demonstration and has stated that “no threat or violence, whatever its motive, whether it’s political, religious or otherwise, will hurt the freedom of expression and freedom of creation.”