Tens of thousands of Parisians gathered in the bitter cold on Wednesday night to express their grief and anger at the attack on the Charlie Hebdo satirical magazine earlier in the day, in which gunmen killed 12.



Some 11 people were also wounded when the attackers opened fire on a meeting of the magazine's editorial staff shortly before midday on Wednesday.



Among the dead were four of France's most popular cartoonists, including editor-in-chief and caricaturist Stephane Charbonnier (who publishes under the pen name Charb) and two policemen. Four of the wounded are reported to be in serious condition.

Police are searching for two brothers from the Paris region, and another man from the Reims area linked to the attack.

Large demonstrations were also held in various locations throughout France, as a shocked nation struggled to come to terms with the country's worst terrorist incident in decades.



Paris prosecutor François Molins told a news conference that police were searching for three suspects, though eyewitness only mentioned two assailants.



Molins said the two gunmen entered the magazines offices at 11.30 A.M. and killed one person in the lobby before climbing to the second floor, where the paper was holding an editorial meeting. It is believed the gunmen knew the time and place of the meeting.



The gunmen opened fire with Kalashnikovs and shouted “Allahu Akbar,” Molins said. They also said they were "avenging the Prophet.” One gunman said the same outside the building after the shooting.



After an exchange of fire with policemen that left at least one officer dead, the gunman fled in a black Citroen. They abandoned the car on the edge of the city, hijacking another in its place.



French President François Hollande will hold a crisis meeting at the Elysée Palace on Thursday morning, Le Figaro newspaper reported. It will include the Prime Minister Manuel Valls and several minister and security services chiefs.

The attack on Charlie Hebdo occurred hours after the magazine tweeted a cartoon of Islamic State (ISIS) leader Abu Bakr al-Baghdadi issuing a New Year's greeting, with the caption: "And especially, health!"

Some 3,000 police flooded the streets of Paris after the attack in search of the attackers. They found the getaway car used by the killers, but no arrests have been reported.

Hollande arrived on the scene shortly after the shooting, and declared that there was no doubt that it was an act of terrorism.

"This is a terrorist operation against an office that has been threatened several times, which is why it was protected," Hollande said. The French president added that "several terrorist attacks" were thwarted in recent weeks.

"A horrific act like the one we saw [in Paris] today will not be the last," unless the Western nations wage a united and determined war against Islamic terror, Prime Minister Benjamin Netanyahu said on Wednesday night in response to the attack on Charlie Hebdo.

The premier conveyed his condolences to the French president and the people of France, saying that "Israel is with France on this difficult day."



He stressed that "the terror of Hamas, Hezbollah, ISIS and Al-Qaeda" won't end "unless the West fights it physically, rather than fighting its false arguments."



The goal of Islamic terror "is not agreement or borders or even Israel," Netanyahu said. "Not mainly Israel and not primarily Israel. The key goal of Islamic terror is to destroy our societies and our countries. To uproot our human culture, which is based on freedom and a culture of choice and to impose in its place a fundamentalist dictatorship which will return humanity to years long past.



"It is absolutely wrong to accept the different justifications offered; we must support each other in a united and aggressive front."

Charlie Hebdo has a history of drawing outrage across the Muslim world with crude cartoons of the Prophet Mohammed. The magazine's offices were firebombed in November 2011 after it published a spoof issue that "invited" Mohammed to be its guest editor and put his caricature on the cover.

Cartoon of the Prophet Mohammed on a November cover of Charlie Habdo. Written from left: “I am the prophet, Idiot,” and from right: “Shut up, infidel”

After Wednesday's attack, security was reinforced at houses of worship, stores, media offices, and transportation following the attack.

Also, Danish media group JP/Politikens Hus, whose newspaper Jyllands-Posten published cartoons in 2005 depicting the Prophet Mohammed, increased its security level because of the shooting, an internal e-mail showed. Jyllands-Posten's publishing of the cartoons sparked a wave of protests across the Muslim world in which at least 50 died.

Meilleurs vux, au fait. pic.twitter.com/a2JOhqJZJM

World leaders react

Foreign Minister Avigdor Lieberman offered his condolences to the French people and government and said that Israel identified with the pain now being felt in France. Lieberman added that it was imperative not to give into terrorists and let them threaten the free world. The West must stand united and determined to fight this danger, he said.

U.S. President Barack Obama condemned the deadly shooting, calling it a terrorist attack against its ally, France. "We are in touch with French officials and I have directed my administration to provide any assistance needed to help bring these terrorists to justice," Obama said in a statement.

British Prime Minister David Cameron described the attack as "sickening" and said Britain stood with France in the fight against terror.

German Chancellor Angela Merkel also condemned the shooting, saying it was "not only an attack on French citizens, but on freedoms of press and speech."

UN chief Ban Ki-moon voiced outrage at the "horrendous, unjustifiable and cold-blooded crime."

The Vatican condemned the attack as "a double act of violence, abominable because it is both an attack against people as well as against freedom of the press," said the Vatican's deputy spokesman, Father Ciro Benedettini. He added that Pope Francis would likely issue a personal condemnation later on Wednesday by sending a message to the archbishop of Paris.

Palestinian President Mahmoud Abbas also came out against the attack, saying that he "strongly condemned and deplored the heinous crime that is in contradiction of religion and morality," in a telegram sent to Hollande, Palestinian news agency Maan reported.

Saudi Arabia, the birthplace of Islam, also condemned Wednesday's shooting attack. "...The kingdom therefore strongly condemns and denounces this cowardly terrorist act that is rejected by true Islamic religion as well as the rest of the religions and beliefs," the Saudi state news agency SPA said, citing an official source.

Egypt's leading Islamic authority, Al-Azhar, also condemned the attack, which killed at least 12 people including two police officers, the worst militant attack on French soil for decades.

UN chief Ban Ki-moon voiced outrage at the "horrendous, unjustifiable and cold-blooded crime."

Russian President Vladimir Putin denounced the attack as a "cynical crime."

"The fight against terrorism can only be effective in the form of a deepened international strategic partnership," Putin's spokesman Dmitry Peskov said.

Mumbai-born novelist Salman Rushdie, who had to go into hiding after then Iranian spiritual leader Ayatollah Khomeini issued a religious edict declaring him an apostate, saying he should be put to death for "blaspheming against Islam" in his novel, The Satanic Verses, also expressed solidarity.

Thank you, @SalmanRushdie pic.twitter.com/R9GDwgk6oZ #JeSuisCharlie

Firefighters carry an injured man on a stretcher in front of the offices of the French satirical newspaper Charlie Hebdo in Paris, January 7, 2015. (Credit: AFP)

French Interior Minister Bernard Cazeneuve and Paris' Mayor Anne Hidalgo arrive at Charlie Hebdo headquarters, January 7, 2014. (Credit: AFP)