WASHINGTON (AP) President Barack Obama called Wednesday's deadly shooting at a satirical newspaper in Paris "cowardly evil attacks" on journalists and a free press and vowed to help France pursue the terrorists who went on the run.

Obama said the attack that left 12 dead in France's deadliest terror attack in at least two decades is a reminder that such tragedies can occur anywhere in the world. He promised to stay vigilant and "hunt down and bring the perpetrators of this specific act to justice, and to roll up the networks that help to advance these kinds of plots."

"The fact that this was an attack on journalists, attack on our free press, also underscores the degree to which these terrorists fear freedom of speech and freedom of the press," Obama said from the Oval Office during a meeting with Secretary of State John Kerry and Vice President Joe Biden .

"But the one thing that I'm very confident about is that the values that we share with the French people, a belief a universal belief in the freedom of expression, is something that can't be silenced because of the senseless violence of the few," he added.

Obama later telephoned French President Francois Hollande from Air Force One en route to Detroit for a speech. Obama offered his condolences and expressed solidarity with Hollande and the people of France, the White House said in a statement. Obama also offered help from the United States as France tries to bring the perpetrators of the attack, and any possible accomplices, to justice.

Hollande thanked Obama for his support and updated the president on steps to care for victims and arrest those responsible, the White House said.

Three masked gunmen stormed the office of the satirical weekly newspaper Charlie Hebdo at noon-time on Wednesday and then escaped in a car. Charlie Hebdo has been repeatedly threatened for its caricatures of the Prophet Muhammad and other controversial sketches.

Witnesses said the shooters shouted "Allahu akbar!" France raised its security alert to the highest level, as thousands honored the victims from Republique Square in Paris.

"What that beautiful city represents the culture and the civilization that is so central to our imaginations that's going to endure," Obama said. "And those who carry out senseless attacks against innocent civilians, ultimately they'll be forgotten."

Earnest said U.S. officials have been in touch with French counterparts but it's "still in the early stages" of figuring out who was responsible for the attack and he couldn't say whether the gunmen were tied to a specific terror group.

"We're still trying to figure out who is responsible for this attack and what their motivations are but as a general matter, we're very mindful of the threat from foreign fighters and the need to try to counter some of the extremist ideology that ISIL is propagating," Earnest said, using an acronym for Islamic State militants.

Asked about what responsibility news organizations had when it comes to publishing provocative material, Earnest said, "There is no legitimate act of journalism however offensive some people might find it that justifies an act of violence, particularly an act of violence on the scale we saw today. That said, it is up to media organizations to make their own decisions about what they choose to publish, what stories they choose to pursue and what sort of commentary they want to broadcast about the world."

Obama called France one of America's strongest allies in dealing with terrorists and said they had been with the U.S. "every moment" since the Sept. 11 attacks.

"For us to see the kind of cowardly evil attacks that took place today I think reinforces once again why it's so important for us to stand in solidarity with them, just as they stand in solidarity with us," Obama said.

Obama said he would be talking with Kerry about protecting Americans living across the globe. Later, Obama counterterrorism adviser Lisa Monaco told MSNBC that there's no evidence of any threat to U.S. personnel in Paris.

Kerry, who has visited Paris more than any other foreign city as America's top diplomat, spoke earlier from the State Department in both English and French to offer America's support.

"I would like to say directly to the people of Paris and of all of France that each and every American stands with you today not just in horror or in anger or in outrage at this vicious act of violence but we stand with you in solidarity and in commitment both to the cause of confronting extremism and in the cause which the extremists fear so much," Kerry said.

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