Amandine Marbach from Strasbourg, France, takes part in a vigil to pay tribute to the victims of a shooting, by gunmen at the offices of weekly satirical magazine Charlie Hebdo in Paris, in the Manhattan borough of New York January 7, 2015.[Photo/Agencies]

The other dead were identified as cartoonists Georges Wolinski and Berbard Verlhac, better known as Tignous, and Jean Cabut, known as "Cabu." Also killed was Bernard Maris, an economist who was a contributor to the newspaper and was heard regularly on French radio.

Le Bechec, the witness who encountered the gunmen in another part of Paris, described on his Facebook page seeing two men "get out of a bullet-ridden car with a rocket-launcher in hand, eject an old guy from his car and calmly say hi to the public, saying 'you can tell the media that it's al-Qaida in Yemen."'

Charlie Hebdo has been repeatedly threatened for its caricatures of the Prophet Muhammad and other sketches. One cartoon, released in this week's issue and titled "Still No Attacks in France," had a caricature of a jihadi fighter saying "Just wait _ we have until the end of January to present our New Year's wishes." Charb was the artist.

In a somber address to the nation Wednesday night, Hollande pledged to hunt down the killers, and pleaded with his compatriots to come together in a time of insecurity and suspicion.

"Let us unite, and we will win," he said. "Vive la France!"

Thousands of people later jammed Republique Square near the site of the shooting to honor the victims, waving pens and papers reading "Je suis Charlie" - "I am Charlie." Similar rallies were held in London's Trafalgar Square as well as Madrid, Barcelona, Berlin and Brussels.

"This is the darkest day of the history of the French press," said Christophe DeLoire of Reporters Without Borders.

Both al-Qaida and the Islamic State group have repeatedly threatened to attack France, which is conducting airstrikes against extremists in Iraq and fighting Islamic militants in Africa.

During Cherif Kouachi's 2008 trial, he told the court, "I really believed in the idea" of fighting the US-led coalition in Iraq.

In the winter 2014 edition of the al-Qaida magazine Inspire, a so-called chief describing where to use a new bomb said: "Of course the first priority and the main focus should be on America, then the United Kingdom, then France and so on."

In 2013, the magazine specifically threatened Charb and included an article titled "France the Imbecile Invader."