PARIS (AP) -- French security forces swarmed a small industrial town northeast of Paris Friday in an operation to capture a pair of heavily armed suspects in the deadly storming of a satirical newspaper. Shots were fired as the brothers stole a car in the early morning hours, said a French security official, who could not immediately confirm reports of hostages taken or deaths later in the day in the town of Dammartin-en-Goele, about 40 kilometers (25 miles) northeast of Paris. Thousands of French security forces have mobilized to find Cherif Kouachi, 32, and Said Kouachi, 34, after the attack on the Charlie Hebdo offices on Wednesday that left 12 people dead. Interior Minister Bernard Cazeneuve confirmed an operation was underway in Dammartin, speaking moments after an emergency meeting with the president, prime minister and top police official. Hours earlier, according to a security official, the brothers stole a Peugeot amid gunfire in the town of Montagny Sainte Felicite, about 50 kilometers (30 miles) northeast of Paris. The official spoke on condition of anonymity to discuss a situation that was still developing. Prime Minister Manuel Valls has said both brothers were known to intelligence services. One brother was convicted of terrorism charges in 2008. Survivors of the bloody assault on Charlie Hebdo said the attackers claimed allegiance to al-Qaida in Yemen. The weekly newspaper had been repeatedly threatened -- and its offices were firebombed in 2011 -- after spoofing Islam and depicting the Prophet Muhammad in caricature. Authorities around Europe have warned of the threat posed by the return of Western jihadis trained in warfare. France counts at least 1,200 citizens in the war zone in Syria -- headed there, returned or dead. Both the Islamic State group and al-Qaida have threatened France -- home to Western Europe's largest Muslim population. The French suspect in a deadly 2014 attack on a Jewish museum in Belgium had returned from fighting with extremists in Syria; and the man who rampaged in southern France in 2012, killing three soldiers and four people at a Jewish school, received paramilitary training in Pakistan.