It's being called the worst terror attack ever in France, and it's put the world on high alert. INSIDE EDITION reports on the attack that left 12 people dead.
Did the Paris terrorists leave tell-tale clues about their identities?
One clue could come from the gunmen's voices.
CNN reported, "They speak French fluently. It almost sounds as though they don't have a foreign accent."
The fact that they spoke such good French means they may be citizens of France.
Another possible clue: the hooded gunmen have military backgrounds.
CNN military analyst retired Lt. General Mark Hertling said, "They're going single shot. They're not doing the typical Jihadi spray and pray technique where they just shoot as many rounds as they can. That tells me that they know how to use weapons."
At least 10 journalists and two police officers were slaughtered in the attack. One cop was executed point blank as he pleaded for his life.
Terrified bystanders fled over the rooftops as shots rang out. They recorded the horror on their cell phones as they huddled behind a low wall, urging each other to stay silent.
The magazine's staff were in their morning meeting when the terrorists struck. The magazine is named Charlie Hebdo, or Charlie Weekly, a tribute to the Peanuts cartoon.
The publication was apparently targeted because it has printed several stories and cartoons mocking Islam.
The killers rampaged through the building seeking out cartoonists and journalists by name.
Among the dead are some of the most famous cartoonists in France. One was 80 years old.
After the slaughter, the killers yelled, "The prophet has been avenged" and ran to a getaway car. One calmly stopped to pick up a sneaker that had fallen out of the vehicle.
Crowds gathered in central Paris at night to mourn the dead.
President Obama pledged American assistance, saying, "These kinds of attacks can happen anywhere in the world."
America is now on alert, concerned about a copycat attack against so-called 'soft targets.'
Former New York City police commissioner Bernard Kerik spoke to INSIDE EDITION's Les Trent. Trent asked, "The obvious and most disturbing question is, could something like that happen here?"
"Yes. There have been 13 attempted attacks in New York City, thwarted attacks since September 11th by the same enemy that took Paris today," replied Kerik.
