Masked gunmen stormed the Paris offices of a weekly satirical magazine known for often ridiculing radical Islam on Wednesday, methodically killing at least 12 people, including the editor and two police officers in the deadliest militant attack on French soil in decade.

Since the French newspaper Charlie Hebdo was known to have a history of drawing outrage across the Muslim world because of its crude Islamic cartoons, it had often been a prime terrorist target for its provocative publications on Islam's holiest figure, Prophet Muhammad.

"We treat the news like journalists. Some use cameras, some use computers. For us, it's a paper and pencil," the Muhammad cartoonist, who goes by the name Luz, told The Associated Press in 2012. "A pencil is not a weapon. It's just a means of expression."

It all began in February 2006 when the satirical magazine decided to publish a series of 12 cartoons depicting the Prophet Muhammad, which had not only been previously featured in the Nordic daily Jyllands-Posten in 2005, but had also sparked intense controversy and anti-Danish protests across the Muslim world since depictions of Prophet Muhammad are strictly forbidden in Islam.

Although the magazine's publication received threats and was forced to place some staff under police protection, no violence had been initiated, Businessweek reported.

The first attack eventually came in November 2011 after the magazine published a spoof issue that "invited" Prophet Muhammad to be its guest editor and put his caricature on the cover. On the following day, the offices of the magazine were firebombed and its website hacked, but there were no injuries.

Chief editor Stephane Charbonnier, who publishes under the pen name "Charb," had defended the Prophet Muhammad cartoons.

"Muhammad isn't sacred to me," he told The AP in 2012. "I don't blame Muslims for not laughing at our drawings. I live under French law. I don't live under Quranic law."

"If we can poke fun at everything in France, if we can talk about anything in France apart from Islam or the consequences of Islamism, that is annoying," he added.

"A year later, the magazine published more Muhammad drawings amid an uproar over an anti-Muslim film," the Associated Press reported. "The cartoons depicted Muhammad naked and in demeaning or pornographic poses. As passions raged, the French government defended free speech even as it rebuked Charlie Hebdo for fanning tensions."

Following the 2012 publication, riot police were posted to guard the magazine's offices, according to the Business Insider.

In 2013, the magazine went further still, publishing what it called a "halal" comic book on the life of Prophet Mohammad.

Although the publication has been described as "crass" by even those who have defended the magazine's right to publish and been condemned once by French foreign minister Laurent Fabius as a "provocation," Charbonnier had maintained that free speech must be upheld and cannot be bounded by what will and will not cause offence.

Unfortunately, it all took a horrific turn on Wednesday after Charlie Hebdo was attacked by gunmen shouting "we have avenged the prophet!" according to Sky News.

Meanwhile, the small-circulation weekly, which makes acerbic commentary on world affairs through cartoons and spoof reports, has also published controversial covers which include retired Pope Benedict XVI in amorous embrace with a Vatican guard; former French President Nicolas Sarkozy looking like a sick vampire; and an Orthodox Jew kissing a Nazi soldier, The Wall Street Journal reported.