A Pakistan-born teenager has admitted to stabbing two people with a meat cleaver outside the former Paris offices of Charlie Hebdo magazine, investigators said Saturday, according to the AFP news agency.
Nine people have now been detained over what the government condemned as "Islamist terror".
The 18-year-old said he wanted to avenge the republication of cartoons of the Prophet Mohammed by the satirical weekly, which in January 2015 was targeted in an attack carried out by Islamist gunmen.
The attack on Friday came three weeks into a trial in Paris of suspected accomplices in the January 2015 attacks on Charlie Hebdo, a policewoman and a Jewish supermarket that left 17 people dead.
While the man is believed to have carried out the stabbings alone, eight other people are now also under arrest following two more detentions Saturday, according to AFP.
The two new individuals arrested were the suspect's younger brother and another acquaintance, a judicial source said.
The man, who said he was born in Pakistan and is 18, "takes responsibility for his action," a source close to the investigation said.
The man mistakenly believed Charlie Hebdo's offices were still in that building and wanted to attack journalists from the magazine, a source close to the inquiry told AFP.
Charlie Hebdo moved offices after the 2015 attack and its current address is kept secret for security reasons.
The two victims were badly wounded but their lives are not in danger.
The magazine received fresh threats from Al-Qaeda this month after it republished the controversial cartoons.
Since the Charlie Hebdo attack, France has been hit by a number of attacks claimed by ISIS, the biggest one being the attack in November of 2015 in which 129 people were murdered.
The country has been under a heightened alert in recent years in the wake of the attacks.