A man armed with a meat cleaver wounded two people in the attack yesterday (25).
The main suspect, identified as an 18-year-old man of Pakistani origin, was arrested near the scene.
Police said six others were in custody and being questioned.
The attack is being treated as a terrorist incident.
Interior Minister Gérald Darmanin said it was "clearly an act of Islamist terrorism".
He said police had underestimated the threat level in the area.