PARIS (AP) — Paris police are facing a modest uptick of unrest in the oft-troubled suburbs of the locked-down French capital, making a small number of arrests after fires were set and fireworks lobbed to shatter the calm imposed by stay-home measures to counter the coronavirus.

A scattering of vehicle and trash-can blazes and firework explosions on the outskirts of Paris this week have so far been far milder than previous outbreaks of violence. But the renewed tensions are also a reminder of policing difficulties that have long simmered in troubled neighborhoods of the city, before the virus lockdown forced most people indoors.

Paris police said officers arrested nine people in two suburbs overnight Tuesday. They were suspected of either possessing fireworks or gathering together to commit violence.

A possible trigger for the flare-up appears to have been a traffic accident this past weekend involving a police car and a motorcyclist who was injured. Police reported that projectiles were thrown at officers following the crash on Saturday evening.

The French lockdown, in place since March 17, has been particularly tough for families jammed together in small apartments in the poorer Paris suburbs. The stay-home orders and police patrols to enforce them have also disrupted underground economies that are centered around drug-dealing and other crime in unruly projects.