Rioters clashed with police in the eastern French city of Grenoble on Sunday night after two teenagers died in a collision with a coach while they were being chased by police.
The teenagers, aged 17 and 19, ran into a coach on a bridge as they fled by scooter late on Saturday evening.
Neither had been wearing a helmet, reports say.
Youths set up barricades and threw petrol bombs at police and set fire to cars in the centre of the city.
Tensions were high for a second night running on Sunday in the Mistral district of the city where the teenagers lived.
Locals accused police of a blunder and one relative told an AFP reporter "you can write that the police were responsible for their deaths".
Around 15 vehicles, including two construction vehicles, were torched while the ground floor of a council department building was destroyed by fire, local media report.
How tragic events unfolded
The two teenagers who died were known to police for petty crime, prosecutors said.
Officials believe the same scooter had been involved in several incidents on Saturday evening - hitting car wing-mirrors, driving without lights and riding on the pavement.
After evading a police check, the two youths then headed for a bridge chased by a police car with its lights flashing.
A coach driver carrying an amateur football team saw the chase in his rear-view mirror while leaving the bridge on a slip-road.
He swerved to the right, apparently to get out of the way, but the scooter tried to overtake on the right at the same time and ended up crushed between the coach and a parapet on the slip-road.
Prosecutors have opened an inquiry but say the coach driver tested negative for drinking and driving.
Grenoble Mayor Eric Piolle urged people to respect the "mourning of the teenagers' families".
Within hours of the accident on Saturday night dozens of people tried to break into a CRS riot police headquarters in the Mistral area but were forced back by tear gas.