Thousands of people congregated in Paris’ Place de la Republique Wednesday for a candlelight vigil for the victims of the deadly shooting at the headquarters of satirical magazine Charlie Hebdo. At least 12 people were killed when masked men armed with assault rifles, shotguns and at least one rocket launcher opened fire on staffers, purportedly to avenge the magazine's depiction of the Prophet Muhammad in cartoons.

The demonstrators held candles, pens and pencils aloft to support Charlie Hebdo staffers and the freedom of the press. “Je Suis Charlie,” or “I Am Charlie,” has become the movement’s unofficial rallying cry. As the protest progressed, silence within the square gave way to chants of “Charlie, Charlie.” Several attendees took to Twitter to post photos and video from the candlelight vigil. 

A live stream of the Charlie Hebdo candlelight vigil can be viewed here, courtesy of the Daily Mirror. Vigils also were organized in London’s Trafalgar Square, Toronto and Berlin. 

Three hooded gunmen attacked the Charlie Hebdo offices Wednesday morning, opening fire amid shouts of “Allahu Akbar” and other Arabic phrases. Two police officers were among the attack’s 12 victims. “We have killed Charlie Hebdo. We have avenged the Prophet Mohammad,” the attackers said in a video of the shooting, according to Reuters.

The unidentified attackers fled the scene in a stolen car and ran over a pedestrian in the process. French authorities are conducting a massive manhunt for the suspects. French President François Hollande said the shooting was a “terrorist attack without a doubt," according to the Washington Post.

“An act of indescribable barbarity has just been committed today in Paris,” Hollande said. “Measures have been taken to find those responsible. They will be hunted for as long as it takes to catch them and bring them to justice.”

U.S. President Barack Obama, the United Nations and the Vatican joined countless international leaders in condemnation of the attack. No group has claimed responsibility for the shooting.