French police have identified the three Islamist gunmen who mounted Wednesday's terrorist attack at a Paris satirical magazine's office and said one had been convicted of terrorism charges in 2008.
Two officials, speaking on condition of anonymity, named the suspects to the Associated Press as Frenchmen Said Kouachi and Cherif Kouachi, in their early 30s, as well as 18-year-old Hamyd Mourad, whose nationality wasn't immediately clear.
One of the officials said they were linked to a Yemeni terrorist network.
Cherif Kouachi was convicted in 2008 of terrorism charges for helping funnel fighters to Iraq's insurgency and sentenced to 18 months in prison.
All three remain at large.
Heavily armed police moved into the city of Reims, in France's Champagne country east of Paris, apparently searching for the suspects. Video from BFM-TV showed police dressed in white apparently taking samples inside an apartment. It was not immediately clear who lived there.
The gunmen moved with the skill and precision of highly-trained commandos, military experts told FoxNews.com.
Masked and garbed in black, the AK-47 wielding assassins appeared to be executing a well-coordinated plan in the late-morning raid, methodically seeking out and executing those targeted for death, and making a clean getaway -- all in the span of a few minutes. Moments after the 11:30 a.m. attack, the three assassins were gone. A manhunt continued into the evening in a shaken and locked-down Paris.
A chilling video of two gunmen stopping their getaway car to wound, chase down and execute a police officer raising his hand in a plea for mercy shows shows tactics and movement that only comes with training, said retired Army Lt. Col. Ralph Peters, a Fox News strategic analyst.
"It was evident immediately that this was a carefully planned, sophisticated operation by well-trained, well-armed veterans of jihad," Peters said. "This was not a pick-up team. These butchers were methodical and efficient. They weren't just terrorists: They were terrorist commandos."
In the video, the killers are seen advancing along the street in perfect unison, seamlessly trading places as one man provides cover fire and the other moves forward. They also were dressed in black tactical gear and balaclavas to conceal their faces.
Peters pointed to the focus and efficiency of the trio, contrasting it with an approach that might be expected of wild-eyed wannabes.
"There aren't little giveaways, it's the overall skill with which the attack was executed," Peters said. "And they didn't just go nuts and shoot wildly, as amateur jihadis do. They set out to kill specific people and never lost focus. [They] even stayed cool during the getaway phase. These men had killed before."
In the aftermath of the attack, images showed a police car's windshield bearing an ominously precise grouping of bullet holes, although it did not appear that the car's occupant was one of the two police officers killed. Still, such accurate shooting is likely not the result of luck, given the powerful recoil of AK-47s.
"These are not amateurs," Scott Stewart, vice president of tactical analysis at global intelligence firm Stratfor, told FoxNews.com. "Especially when you compare it to the [deadly, but amateurish lone wolf attack on Oct. 22, 2014] in Ottawa.
"These men were working as a fire team," he said.
Stewart believes the killers, who witnesses said spoke unaccented French, likely were trained in the Middle East and had possibly seen battle there. More that 1,000 French jihadists are estimated to have left to fight alongside terrorist groups like Islamic State and Al Qaeda, stoking fears that they would continue to kill in the name of Islam upon return.
"It's possible that they were trained in Yemen or anywhere on the Arabian Peninsula," Stewart said. "This was a highly trained team. They were trained in small arms and small unit tactics. What they were displaying is guerrilla warfare 101."
Stewart noted that the Russian-made AK-47s are the weapon of choice for terrorists in training camps as well as on the battlefields of Iraq and Syria.
Stewart also said that it is likely that the gunman were already known to authorities in France.
"I would bet cash that these guys were known to the police," he said. "But it is hard to track them, especially in France, where there are so many of them."