France's government called for calm on Thursday after a teenage motorcyclist died in a collision with a police car, two months after a fatal shooting triggered riots.
Officers claim the 16-year-old boy was fleeing a traffic stop when he crashed into a police vehicle in Elancourt, west of Paris. He died of his injuries in hospital.
Two officers were taken into custody as prosecutors look into a possible case of manslaughter after Wednesday's collision.
The case evoked memories of the June 27 incident in which a 17-year-old boy of North African descent was shot and killed during a traffic patrol in Nanterre.
The shooting of Nahel M led to successive nights of rioting and reignited grievances about policing and racial profiling in France's suburbs.
Extra police have been deployed to Elancourt to head off potential unrest after the latest incident, AFP reported. The men's Rugby World Cup kicks off in Paris on Friday.
French government spokesman Olivier Veran said the investigations under way would determine the "exact circumstances" of Wednesday's death.
Prosecutors were also investigating police allegations that the teenager failed to stop while riding his motocross bike along the pavement.
"Obviously I am calling for calm.... I am calling for restraint and careful consideration," Mr Veran said on France Inter radio.
"Regardless of how dramatic a situation is, it needs answers that we do not yet have."
Britain's King Charles III is due in France for a rearranged state visit this month. His trip was planned for March but postponed during a separate round of protests over President Emmanuel Macron's pension reforms.
Paris will also host the summer Olympics and Paralympics in 2024, with preparations for the torch relay already overshadowed by unrest. City officials hope the showpiece will leave a legacy of better sporting facilities for young people in the underfunded suburbs.