NEW YORK (CBSNewYork/AP) -- A crowd gathered in Union Square Wednesday night to mourn the victims of the massacre of at least 12 people in a terror attack on a Paris newspaper.
Meanwhile, one of the suspects in the shooting surrendered to police in Paris late Wednesday New York time, while two more remained at large.
Hundreds of people were seen in Union Square, singing the French national anthem and holding images of the eyes of the victims and signs with the hashtag #JeSuisCharlie, or "I am Charlie," referring to the Charlie Hebdo weekly that was attacked, CBS2's Tony Aiello reported.
"I think it's amazing how quickly people rose up and are pushing back on this," said Brian Borkowsky of Ditmas Park, Brooklyn.
"These guys just proved today that laughter has become a very dangerous job," said French citizen Rick Therie.
Earlier in the day, police Commissioner Bill Bratton called the attack on the Paris offices of the satirical newspaper "very concerning."
He said a detective assigned to Paris has been relaying information on the attack, allowing police here at home to monitor the incident.
"We will always err on the side of caution and fortunately we have the resources to do quite a lot, even without a direct threat," Bratton said.
Since the attack, extra officers have been stationed at various locations throughout the city, including the French Consulate. Deputy Commissioner for Intelligence and Counterterrorism John Miller said the NYPD is taking precautions.
"We look at the critical response vehicles," he told WCBS 880's Peter Haskell. "These are the marked units at potentially sensitive or target locations. We redeploy them based on the world events or the particular threat stream of that moment."
Mayor Bill de Blasio called the incident "a heinous terrorist attack" that was an attack on the news media and on freedom of expression.
Bratton: No Direct Threat To NYC Following Terror Attack On Paris Newspaper
He said he called Paris Mayor Anne Hidalgo Wednesday morning to offer his condolences and to express New York City's "unwavering support for the people of Paris."
France On High Alert; Gunmen At Large
French police officials identified three men as suspects in the deadly attack as French nationals.
Two officials named the suspects as Frenchmen Said Kouachi and Cherif Kouachi, who are brothers and in their early 30s, as well as 18-year-old Hamyd Mourad, whose nationality wasn't immediately clear.
A judicial official said the youngest suspect had turned himself in to police, but there was no official confirmation from authorities.
Early Thursday Paris time, French police released images of the two other suspects, named as Cherif Kouachi and Said Kouachi, saying they should be considered armed and dangerous.
Three masked gunmen shouting "Allahu akbar!'' stormed the Paris offices of Charlie Hebdo Wednesday, killing 12 people, including its editor, before escaping in a car.
Charlie Hebdo has been repeatedly threatened for its caricatures of the Prophet Muhammad and other controversial sketches.
Security forces were hunting for the gunmen who spoke flawless, unaccented French in the military-style attack.
A cartoonist who survived the attack said the shooters claimed to be Al-Qaeda members.
French President Francois Hollande called the slayings "a terrorist attack without a doubt'' and said several other attacks have been thwarted in France "in recent weeks.''
France raised its security alert to the highest level and reinforced protective measures at houses of worship, stores, media offices and transportation. Schools closed across Paris. Top government officials held an emergency meeting and Hollande planned a nationally televised address in the evening.
There was no immediate claim of responsibility for the attack. It was France's deadliest terror attack in at least two decades.
Clad all in black with hoods and carrying machine guns, the attackers forced one of the cartoonists arriving at the office building with her young daughter to open the door with a security code.
The staff was in an editorial meeting and the gunmen headed straight for the paper's editor, Stephane Charbonnier, widely known by his pen name Charb, killing him and his police bodyguard, said Christophe Crepin, a police union spokesman on the scene.
Minutes later, two men strolled out to a black car waiting below, calmly firing on a police officer, with one gunman shooting him in the head as he writhed on the ground.
In addition to Charbonnier, the journalists killed in the attack were cartoonists Georges Wolinski, Jean "Cabu" Cabot, Bernard "Tignous" Verlhac, and Philippe Honore; journalist and economist Bernard Maris; psychoanalyst and columnist Elsa Cayat; and copy editor Moustapha Ourrad.
Police officers Franck Brinsolaro and Ahmed Merabet, cultural event organizer Michel Renaud who was visiting the magazine office; and janitor Frédéric Boisseau were also killed.
"Hey! We avenged the Prophet Muhammed! We killed Charlie Hebdo,'' one of the men shouted, according to a video filmed from a nearby building and broadcast on French television. Other video images showed two gunmen in black at a crossroads who appeared to fire down one of the streets. A cry of "Allahu akbar!'' -- Arabic for "God is great''-- could be heard among the gunshots.
The video showed the killers moving deliberately and calmly. One even bent over to toss a fallen shoe back into the small black car before it sped off. The car was later found abandoned in northern Paris, police said.
Corinne Rey, the cartoonist who said she was forced to let the gunmen in, said the men spoke fluent French and claimed to be from al-Qaeda. In an interview with the newspaper l'Humanite, she said the entire shooting lasted perhaps five minutes.
Authorities were said to be paying close attention to a moment when a gunman appears to raise his fingers in the air, possibly signaling another car or person. The behavior is being studied by authorities around the world.
"Looking at the videos, they walked when they need to walk, they run when they need to run, they don't seem to be concerned about effecting their escape as much as they are concerned about executing their missions," Miller explained.
World leaders including President Barack Obama and German Chancellor Angela Merkel condemned the attack, but supporters of the militant Islamic State group celebrated the slayings as well-deserved revenge against France.
Mohammed Moussaoui, president of the Union of French mosques, condemned the "hateful act,'' and urged Muslims and Christians "to intensify their actions to give more strength to this dialogue, to make a united front against extremism.''
Obama: French Shooting 'Cowardly Evil Attacks'
President Obama called Wednesday's deadly shooting "cowardly evil attacks'' on journalists and a free press and vowed to help France pursue the terrorists who went on the run.
He said the attack 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.
The president pointed to shared values between the U.S. and France.
"The values we share with the French people, a belief, a universal belief in freedom of expression is something that can't be silenced," President Obama said.
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. He said he hoped to speak later in the day with Hollande.
'Worst Tragedy In Cartooning History'
Earlier back in New York, editorial cartoonists were shaken by the news, 1010 WINS' Mona Rivera reported.
"This news has just spread like wild-fire throughout the American political cartooning community. Everybody is in absolute shock," Jack Ohman said.
American Cartoonists Shaken By Terror Attack On French Publication
Ohman's cartoons have appeared in the New York Times and New York Daily News, among other publications.
He's now president of the Association of American Editorial Cartoonists, which has condemned the killings in Paris.
"This is the worst tragedy in cartooning history," Ohman said, adding that cartoonists are determined not to let this attack keep them from political satire about terrorists.
Charlie Hebdo has been repeatedly threatened for its caricatures of the Prophet Muhammad and other sketches.
Its offices were firebombed in 2011 after an issue featured a caricature of the prophet on its cover. Nearly a year later, the publication again published Muhammad caricatures, drawing denunciations from the Muslim world because Islam prohibits the publication of drawings of its founder.
Another cartoon, released in this week's issue and entitled "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.
As CBS2's Dick Brennan reported, vigils were being held across the country with people holding pens, pencils, signs, and candles. France planned to observe a day of mourning on Thursday for those killed in attack.
On social media, supporters of militant Islamic groups praised the attack. One self-described Tunisian loyalist of al-Qaeda and the Islamic State group tweeted that the attack was well-deserved revenge against France.
The hashtag "JeSuisCharlie" was trending as people expressed support for the weekly and for journalistic freedom. The weekly's website collapsed earlier Wednesday but was later restored.
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