Two people known to the authorities were killed in the shooting late Sunday in the southern town of Ollioules west of the French port city of Toulon, police said.
But the shootout also claimed the life of a woman, 57, who was a passenger on a scooter and is believed to be an innocent victim caught in the crossfire, police said.
“All means will be used to identify and arrest those behind the shooting in Ollioules,” said Interior Minister Christophe Castaner on Twitter, expressing confidence in the police to “eradicate the criminal networks who corrupt our neighbourhoods.”
A police source said the profile of the two male victims — aged 29 and 30 and known to police over past drug cases — backed up the idea that the shooting was a settling of accounts between gangs.
The two gunmen escaped the scene.
The female victim was on a scooter driven by her husband, 58, who was wounded and taken to hospital. Local media said they were regular visitors to the area.
The Var department of southern France — a tourist magnet for its balmy Mediterranean climate — has seen a string of gangland-style shootings in the last months.
In March, notorious local crime figure Thierry Fornasari, who had been on the run since 2017, was shot dead in the town of Tanneron.
Five days later a man aged 20 was gunned down in the same region.