PARIS (AP) — A judicial official says investigators are still questioning the parents and a friend of the man who attacked passers-by with a knife in a central Paris neighborhood.

The 20-year-old Frenchman, born in the Russian republic of Chechnya, killed one person and wounded four others in Saturday attack, before police fatally shot him. The Islamic State group claimed responsibility.

Khamzat Azimov's parents and a friend from the eastern city of Strasbourg were being detained by police.

The official said Monday the suspect was living in the northern 18th district of Paris with his family, which had previously lived in Strasbourg.

The official wasn't authorized to speak publicly on the ongoing investigation.

Counterterrorism investigators want to know if the assailant had help or co-conspirators.