Charlie Hebdo under attack in Paris

The French satirical magazine Charlie Hebdo was attacked on Wednesday by terrorists who worked methodically through its Paris office with Kalashnikovs killing 12 people including two policemen.

Charlie Hebdo was known for its provocative cartoons. Some of them mocked Islamic extremism, and they often portrayed the Prophet Mohammed, a fact that in itself is considered an insult and profound religious violation by many Muslims. Charlie Hebdo’s offices were bombed in 2011, after the magazine released an issue in which the Prophet Muhammad was satirically billed as “guest editor.” The issue included a cartoon of Muhammad and was renamed “Charia Hebdo,” a reference to Shariah law. In the fall of 2012, Paris police called and urged Stéphane Charbonnier, the editorial director of Charlie Hebdo, to stand down on his plans to publish cartoons of prophet Mohammed in his satirical weekly. Charbonnier, who is also a cartoonist for the newspaper, refused, citing his rights as a journalist and the publication's ethos of using satire to express its leftist, secular politics.

President François Hollande of France declared Thursday a national day of mourning after a terror attack on the French satirical newspaper and pledges to defend the freedom of press.

12 people were killed by hooded gunmen shouting Islamic phrases in the incident. The gunmen armed with Kalashnikovs fled in a stolen car in the Paris suburb after exchanging gunfire with police. There were reportedly three attackers of which French police have taken Hamyd Mourad, 18, into custody after he surrendered to authorities. The two central suspects in the attack remain at large; regional police issued a new plea for help in finding two French-born brothers, Said and Cherif Kouachi, both in their 30s.

France reinforced security at houses of worship, stores, media offices and transportation after masked gunmen stormed the offices of the satirical newspaper on Wednesday

Ambulances gather in the street outside the French satirical newspaper Charlie Hebdo's office, in Paris on Wednesday

Demonstrators gathered at the Place de la Republique in paris to show support to the newspaper and condemn the brutal attack

People gather in solidarity for the victims of the attack