Catherine Herridge reported on "America's Newsroom" that U.S. intelligence and counterterrorism officials are deeply engaged in the deadly terror attack in Paris.

Herridge said what has drawn officials' attention is the level of preplanning and premeditation the attack appears to exhibit.

She said that according to eyewitness accounts, the assailants asked for certain individuals at Charlie Hebdo's newspaper offices by name.

"In addition, the assailants showed skill and ruthlessness with their targeting," Herridge reported. "Think of the video of that wounded French police officer being executed, shot in the head at point blank range as he lay in the street."

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Herridge added that the fact that the gunmen were able to extract themselves and make a getaway again shows premeditation and advanced reconnaissance of the site.

"There are two buckets of suspects based on the preliminary information, the homegrown, self-radicalized individual or those who have traveled to Syria and gained training from Al Qaeda or ISIS," Herridge said, noting that more than 1,000 French nationals have recently traveled to that region.

She said that the priority for U.S. counterterrorism officials is identifying the suspects, and they will use television footage, CCTV footage, physical evidence and DNA evidence to that end.

Herridge said the focus will be determining whether this is a single incident or a series of attacks.

She said that today's attack, based on the reporting of at least four individuals and three shooters being involved, appears to be the work of a small cell.

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