Damian Grammaticas describes seeing armed police and military helicopters in the area around the service station allegedly robbed by the suspects.The two main suspects in the Islamist attack on Charlie Hebdo magazine in Paris are said to have robbed a service station in the north of France.
They stole food and petrol, firing shots as they struck at the roadside stop near Villers-Cotterets in the Aisne region, French media report.
France has observed a minute's silence for the 12 people killed at the office of the satirical magazine.
Earlier in the day, a gunman shot dead a policewoman south of Paris.
A second person was seriously injured in the attack in Montrouge, after which the gunman fled.
It is unclear if the attack is related to the pursuit of prime suspects Cherif and Said Kouachi.
French police released photos of the Kouachi brothers - Cherif (L) and Said (R)According to the manager of the service station that was robbed on the RN2 road in Aisne at about 10:30 (09:30 GMT), the attackers fit the description of the two men, and were heavily armed with Kalashnikovs and rocket-propelled grenade launchers.
They are said to have driven off in the direction of Paris in a Renault Clio car, apparently the same vehicle hijacked in Paris soon after the Charlie Hebdo attack.
According to French commercial channel BFMTV, police are monitoring all of the main entry roads into the capital.
Meanwhile, the lawyer for Charlie Hebdo, Richard Malka, confirmed that next week's edition of the magazine would go ahead on Wednesday and would have a print run of one million, instead of the normal 60,000 copies.
Those killed (from left) include economist Bernard Maris, prominent cartoonists Wolinski and Cabu, Charlie Hebdo editor Stephane Charbonnier and cartoonist Tignous