Counter-terrorism officers are investigating what authorities called an Islamic extremist attack linked to Charlie Hebdo, which lost 12 employees in an al-Qaida attack in 2015.
The weekly, which routinely mocks religious and other prominent figures, recently republished caricatures of the Prophet Muhammad that outraged many Muslims.
Two people were injured in the attack on Friday. Officials have said their wounds are not life-threatening.
French interior minister Gerald Darmanin said the suspected assailant had been arrested a month ago for carrying a screwdriver, but was not on police radar for Islamic radicalisation.
He said the screwdriver had been considered a weapon at the time.
The suspect arrived in France three years ago as an unaccompanied minor, apparently from Pakistan, but his identity is still being verified.
Seven other people were detained in the aftermath of Friday’s attack, but one has been released, according to judicial officials.
Five of those in custody were detained in the Paris suburb of Pantin in a residence where the suspect is believed to have lived, a police official said.
A woman and a man were wounded in Friday’s attack. They had been working at a documentary production company, and had stepped outside for a cigarette break.
The interior minister conceded that security was lacking on the street where Charlie Hebdo was once headquartered, and ordered special protection for all “symbolic sites”, noting in particular Jewish sites around the Yom Kippur holiday this weekend.
A Jewish grocery store was targeted days after the Charlie Hebdo newsroom massacre, in what authorities say were coordinated attacks.
