French police swooped down on suspected Islamist networks Friday, arresting 19 people as President Nicolas Sarkozy vowed a crackdown would continue after an extremist gunman's killing spree. According to the French Press Agency (AFP), the arrests took place in several cities including Toulouse, where Mohamed Merah was shot dead by police last week after a series of cold-blooded shootings in southwestern France that left seven dead. Sarkozy said the arrests targeted "radical Islam" and that the trauma in France after the shootings in Toulouse and Montauban was somewhat like that felt in the United States after the September 11, 2001 attacks. "What must be understood is that the trauma of Montauban and Toulouse is profound for our country, a little -- I don't want to compare the horrors -- a little like the trauma that followed in the United States and in New York after the September 11, 2001 attacks," he told Europe 1 radio. Agents from France's DCRI domestic intelligence agency working with anti-terror and elite police units carried out the dawn raids in Toulouse, Nantes, Marseille, Lyon, Nice, Paris and other areas. The operation "is not linked only to Toulouse, it's on all of French territory, is linked with a form of radical Islam and is in full accordance with the law," Sarkozy said. He said Friday's operation was only the start. Police said Kalashnikov assault rifles and other weapons were seized during the raids. Among those arrested was Mohammed Achamlane, the head of a suspected extremist group called Forsane Alizza, the sources said, with three Kalashnikovs, a Glock pistol and a grenade were seized from his home. The arrests came a day after Merah, who was shot dead by a police sniper on March 22 at the end of a 32-hour siege at his flat in Toulouse, was buried in the city under heavy police watch. The 23-year-old had shot dead three soldiers, and three children and a teacher at a Jewish school in a killing spree that shocked the country.