Cartoonists worldwide responded to the killings of 12 people at satirical French magazine Charlie Hebdo, with many posted on Twitter with #JeSuisCharlie.

Wednesday’s slaughter at the Paris offices of satirical magazine Charlie Hebdo will only increase French Jews’ fears for their security, the president of the French Jewish organization CRIF told The Algemeiner.

Roger Cukierman also said he expects a high rate of French aliyah to Israel this year after about 6,000 French Jews emigrated in 2014.

A French-Israeli artist and activist, Ron Agam, told The Algemeiner: “Paris today, like New York and Jerusalem, has been the victim of an act of barbarism. We are under attack from a merciless fanatical ideology.”

French police are seeking two brothers, Said and Cherif Kouachi, in the killings of 12 people at Charlie Hebdo even while dealing with the killing of policewoman Thursday, the BBC reports.

Jewish leaders and organizations were quick to condemn the Charlie Hebdo attack and offer support to France.

“Our thoughts and prayers are with those affected by attack today at the French satirical newspaper Charlie Hebdo,” the Jewish Federation of Greater Atlanta tweeted.

“The people of Israel send their condolences to the people of France over the brutal acts of savagery in the heart of Paris today,” Prime Minister Benjamin Netanyahu said. “The attacks of radical Islam know no boundaries. These are international attacks, and the response has to be international. The terrorists want to destroy our freedoms and our civilization.”

In a letter to French Ambassador Gérard Araud, B’nai B’rith International President Allan J. Jacobs and Executive Vice President Daniel S. Mariaschin offered condolences and prayers: “For over 170 years, B’nai B’rith International has condemned all senseless acts of violence. Today we recognize global terror as one of the world’s greatest challenges, and we have remained steadfast in our efforts to combat it.”

The American Jewish Committee said it was appalled by the Paris slaughter. “Islamic terrorism has struck once again in the heart of our beloved France,” said Simone Rodan-Benzaquen, the director of AJC Paris. “Their target was both those who worked at the magazine and the laudable values of an open, democratic society they embodied. There can be no compromise with such murderers and their heinous worldview.”

The Anti-Defamation League, while noting its past criticism of Charlie Hebdo’s provocative attacks on a wide range of religious groups, called the attack a “dreadful reminder” of attacks on Jewish sites in France. “Terrorism is never justified, and freedom of the press must be protected,” ADL National Director Abraham Foxman said. “Newspapers must be free to publish controversial content, not without criticism, but without intimidation or violence.”

Foxman also highlighted the attack’s “swift and unconditional condemnations by mainstream of French Muslim leaders.”