The suspect, identified only as Kévin T., admitted to planning the attacks near Paris last week, the prosecutor said. One person was killed and seven wounded.

A man accused of killing one person and wounding seven in a shooting spree near Paris last week admitted that he had targeted people “of a Muslim, African or North African type,” France’s antiterrorism prosecutor said at a news conference on Thursday.

The suspect is 39 and has been identified only as Kévin T. by French officials. He acknowledged planning the attack in advance, telling investigators he had chosen the area because it was a “den of Islamists,” according to the prosecutor, Olivier Christen. The shootings took place last Friday in Trappes, a working-class city with a large Muslim and immigrant population and the neighboring town of La Verrière, both southwest of Paris.

Kévin T., who initially denied having been motivated by race, rejected the authorities’ characterization of the attack as terrorist, saying his conduct was legitimate, Mr. Christen said. He said he had not intentionally gone after children — an 11-year-old was among the wounded — but felt no regret, according to the prosecutor. The suspect’s lawyer, whose identity has not been made public, could not immediately be reached for comment.

Kévin T. has not been formally charged with a crime. Mr. Christen said he would be investigated on charges including murder and attempted murder “in connection with a terrorist enterprise,” with his apparent racial or ethnic motivation an aggravating circumstance. He was taken into police custody after the shooting, and prosecutors asked on Thursday that he be placed in pretrial detention.

The shootings came at a tense time for France, which was recently rocked by protests and riots, and they have become a political issue as next spring’s presidential election draws nearer. In a YouTube interview on Wednesday night, President Emmanuel Macron said the attack should be a “wake-up call” for the country.

“There’s a kind of disinhibition in what people say, an atmosphere of racism,” Mr. Macron said, accusing France’s main far-right party, the National Rally, and its affiliates of letting racism permeate the public debate.

The gunman fired 128 rounds from a nine-millimeter Sten submachine gun at eight locations along a route of about seven miles, often from his car, according to the authorities.

He shot and killed Pengo Bossio Wangi, 26, in a park in Trappes. He fired at several people at a Trappes gas station, leaving one seriously wounded. He severely wounded three other people, including the 11-year-old, at two locations in La Verrière. At four other sites, he fired at eight people, including a 12-year-old, but missed them, according to Mr. Christen. The gunman opened fire at eight locations, including this Trappes gas station, the authorities said.

Antony Paone/Reuters Three of the seven people wounded were still hospitalized on Thursday, including one whose life was still in danger, Mr. Christen said. He said earlier this week that the 11-year-old would survive.

After being taken into custody, Mr. Christen said, Kévin T. carried out acts of self-harm, made incoherent statements and was taken to a hospital and given a psychiatric examination. The exam concluded that he did not show signs of an “incapacitating psychiatric disorder that could justify involuntary hospitalization,” Mr. Christen said.

He said the suspect had been taking antipsychotic medication daily and claimed to be schizophrenic but that the psychiatrist who examined him questioned that assertion, saying that his medication was mild. Toxicology tests found traces of the medication in his blood, the prosecutor said.

Kévin T. told investigators that he had started using drugs at 13 — traces of cocaine and cannabis were found in his blood, Mr. Christen said — and that he suffered from psychological problems, for which he was briefly hospitalized at 25 and was still being treated.

The investigation showed that Kévin T. had extensively planned the attack, the prosecutor said. He bought the gun last month, and he had paid family debts and put other personal affairs in order, according to Mr. Christen. Two days before the shootings, he deleted all his social media accounts and sold his laptop. His phone “required extensive investigative work to locate,” Mr. Christen said.

His home was booby-trapped with an explosive device, which the police defused, Mr. Christen said. They found weapons there, including “brass knuckles, a steel bayonet and a silencer,” and books including a Quran, a Bible and Hitler’s “Mein Kampf,” the prosecutor said.

The police also found more than 200 stickers expressing support for law enforcement and pride in being French, 30 of which bore the acronym of the National Rally. Kévin T. said he was not affiliated with any political party but had once “infiltrated” left-wing groups, according to Mr. Christen. He told investigators he was single and had a full-time job.

Since the shootings, public gatherings have been held in La Verrière, in Paris and elsewhere to protest racism and honor the memory of Mr. Bossio Wangi, the man who was killed. The government has said that Prime Minister Sébastien Lecornu would preside over a national tribute to Mr. Bossio Wangi at a date to be announced after discussions with his family.