Three men armed with Kalashnikov rifles entered the HQ of satirical magazine Charlie Hebdo in Paris this morning, around 11:30 AM local time. Twelve people, including two policemen, were killed.

According to the French press, 20 people were also injured. The cartoonists Cabu, Wolinski, and Charb were among the victims. Stéphane “Charb" Charbonnier was also director of the magazine and was on al-Qaeda's Most Wanted list.

“France is in a state of shock," said President François Hollande. “This is undoubtedly a terrorist attack," he added, denouncing it as an act of “exceptional barbarity." Hollande arrived at the crime scene within hours of the attack, as did Interior Minister Bernard Cazeneuve, Culture Minister Fleur Pellerin, and Paris Mayor Anne Hidalgo.

A large-scale operation has been launched to catch the gunmen who fled the scene in a hijacked vehicle.

The attack was thought to be an act of revenge. A video originally broadcasted by BFM TV shows one of the assailants saying: “We've avenged Prophet Muhammad. Charlie Hebdo is dead."

The magazine is notorious for its contentious depictions of the Prophet. In 2006, it was sued by several Muslim organizations after the magazine published controversial cartoons of the Prophet, which had originally appeared in the Danish newspaper Jyllands-Posten.

In 2011, Charlie Hebdo's offices were fire-bombed following its November 3 issue, entitled “Charia Hebdo," which was said to have been “guest-edited" by Muhammad.

This morning, approximately one hour before the attack, the magazine tweeted a cartoon of ISIS leader Abu Bakr al-Baghdadi wishing “good health" as a New Year's message to Twitter followers.

The White House has firmly condemned the attack. Britain's Prime Minister described the murders as “sickening" in a statement posted on Twitter.

This is the most deadly attack in Paris since the 1995 bombing at Saint Michel Station, which killed eight people and wounded 80.