PARIS - Three heavily-armed masked gunmen opened fire in the Paris office of French satirical magazine Charlie Hebdo on Wednesday, killing 12 people.
The country has raised the alert status in its capital to the highest level, with French President Francois Hollande condemning the terror attack "of exceptional barbarity".
Charlie Hebdo is no stranger to controversy. It has never pulled its punches when it came to lambasting religion, especially radical Islam.
Here are five things to know about the weekly magazine.
1. It was banned because of controversial headline
It was first launched in 1960 as a monthly title called Hara-Kiri. In 1969, Hara-Kiri Hebdo, a weekly publication focusing on current affairs, was launched. Hebdo is French for a weekly magazine.
It was banned in 1970 after leading with a headline, "Tragic Ball at Colombey, one dead", that mocked two significant events that year - a discotheque fire which killed more than a 100 people, and the death of former French president General Charles de Gaulle.
In order to sidestep the ban, a new weekly named Charlie Hebdo was born. The name was derived from the "Peanuts" cartoons featuring Charlie Brown, and a nod to Charles de Gaulle. It was published until 1981, when it folded because of declining readership and lack of resources. It was revived in 1992 by members of the original team.
It uses satire to target politicians, police, bankers and religion with its inflammatory headlines and garish cartoons. It has often been compared to a rival but more prestigious publication, Le Canard Enchaine, which features investigative journalism and leaks from within the French government.
The weekly wore its irreverence as a badge of honour. When a reader accused editors of being "dumb and nasty" in an early letter, they adopted the phrase as an official slogan, reported the Financial Times.
2. Known for lambasting religion, especially radical Islam
From publishing the Danish cartoons of Prophet Muhammad in 2006 to renaming an edition "Sharia Hebdo" in 2011 and listing Islam's prophet as its supposed editor-in-chief, the weekly has repeatedly caricatured Muslims and their beliefs.
Politically left-libertarian, it has gleefully fired barbs at other religions, such as the Catholic Church when it was mired in child sex abuse scandals several years ago.
But its attacks on Muslims have caused the most controversy, including a court case on charges of racism and the firebombing of its offices in 2011 after the "Sharia Hebdo" edition.
The weekly has also made fun of the Muslim veil for women and ridiculed Islamist extremists. In the edition publishing the Danish cartoons which sparked Middle East riots in 2005, its cover had a drawing of Prophet Muhammad in tears, saying: "It's hard to be loved by jerks".
3. Seen by some as a symbol of free speech and press
Despite courting controversy, it has received support from former president Nicholas Sarkozy, notable politician François Bayrou and Mr Hollande. Mr Sarkozy had defended Charlie Hebdo as a newspaper "following an old French tradition, satire".
4. Security at the Charlie Hebdo office is a common sight
Police said the weekly had received several threats in recent weeks and had permanent police protection.
Magazine editor Stephane Charbonnier, who was reportedly among the 12 killed, was the target of death threats and had bodyguards accompanying him.
Riot police were deployed at the magazine's offices in 2012 in anticipation of the backlash it would receive for featuring a naked Prophet Muhammad cartoon.
5. Last words before the attack
Just moments before Wednesday's attack, the magazine had posted a cartoon picture of Abu Bakr al-Baghdadi with a caption wishing the leader of the Islamic State in Iraq and Syria (ISIS) group a happy new year and particularly good health moments on its Twitter and Facebook.
Its cover this week also featured the new novel, which satirises France under a Muslim president, by controversial French author Michel Houellebecq.
Sources: Reuters, Financial Times, Guardian, BBC