PARIS — Eight days after the police shot dead the self-confessed killer of four Jews and three French paratroopers in southwestern France, elite units on Friday raided localities in several parts of the country and detained 17 people described as Islamic militants.


In the early hours, officers raided addresses in Toulouse — where the gunman, Mohammed Merah, 23, was slain after a 30-hour siege last week — in the Paris region and in southern and western cities including Nantes, French media reports said. Two people were held briefly and released, while 17 others remained in custody.


President Nicolas Sarkozy said Kalashnikov assault rifles had been seized in the raids, which, he told Europe 1 radio, “are going to continue” and would lead to “a certain number of people” being expelled from France.


“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.


The raids came just weeks before the first round of a presidential election in which law-and-order issues could swing decisive votes. Mr. Sarkozy, thus, is seeking to project an image of firm leadership and resolve in the face of a broader threat.


The authorities drew no immediate link between those arrested and the Toulouse shootings. Mr. Sarkozy had earlier demanded that the police evaluate the threat presented by people regarded as sympathetic to militant Islam.


In three attacks spread over several days, Mr. Merah was accused of killing three French soldiers in southwestern France before he attacked a Jewish school in Toulouse last week, killing three children and a rabbi. The killings were all the more lurid in light of Mr. Merah’s claim to have filmed them as he shot his victims using a handgun before speeding away on a scooter.


The Paris bureau of the Al Jazeera satellite broadcaster said earlier this week that a copy of the video had been sent to its offices but it decided against broadcasting the images.


Investigating judges on Sunday had already filed preliminary murder and terrorism charges against Mr. Merah’s older brother, saying that the killer acted with his guidance. The brother, Abdelkader Merah, 29, was described by the police as an Islamic radical who reportedly had ties to at least one jihadist network. The brother denies involvement in the fatal shootings, his lawyer said.


Although Mohammed Merah told the police that he had acted alone, investigators believe that he operated “under the influence of his brother,” said Élisabeth Allannic, a spokeswoman for the office of the prosecutor in Paris, which handles terrorism cases.


The body of Mr. Merah was buried on Thursday after disputes over where it should be interred. The authorities in Algeria, where his father lives, refused to accept it and municipal authorities in Toulouse were also reluctant to permit the burial until Mr. Sarkozy stepped in on Thursday to order the interment in the city.


French media reports said Friday that around 30 people attended the burial, and a handful of them had wished to chant Islamist slogans.


French police said the arrests were not directly linked to the shootings to which Mr. Merah admitted before his death but rather to dismantle networks of known militant sympathizers.


Among the cities where arrests took place, Nantes had already figured in police investigations after the Interior Ministry in January closed down a small militant group, Forsane Alizza, accused of extremist views. Before the authorities closed down its Web site, the group said it sought to recruit “soldiers,” though for what purpose remained unclear. The leader of the group, Mohammed Achamlane, has denied that the group is seeking jihadist recruits, but he was among those detained onFriday, news reports said.


The group has also denied having links to Mohammed Merah. Law enforcement officials have been examining whether Mr. Merhad was involved in the group, which has publicly decried Islamophobia in France.