Seven people were in custody Saturday after a stabbing outside the former Paris offices of satirical newspaper Charlie Hebdo, including the suspected assailant, authorities said.
Counterterrorism authorities 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.
The suspected assailant in Friday's stabbing had been arrested a month ago for carrying a screwdriver but was not on police radar for Islamic radicalisation, Interior Minister Gerald Darmanin said. He said the screwdriver was considered a weapon, but did not explain why.
The suspect arrived in France three years ago as an unaccompanied minor, apparently from Pakistan, but his identity was still being verified, the minister said.
Seven others 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.