Nearly 80 French police officers have been injured, six seriously, during a second night of riots by youths in the suburbs of Paris, police unions say.
The police say some officers suffered bullet wounds, while others were hurt by stones, fireworks and petrol bombs thrown at them in Villiers-le-Bel.
The youths said they were avenging the two teenagers killed when their motorcycle hit a police car on Sunday.
A senior union official said the riots had been more intense than in 2005.
The 2005 unrest, sparked by the accidental deaths of two youths, spread from a nearby suburb of Paris to other cities and continued for three weeks, during which more than 10,000 cars were set ablaze and 300 buildings firebombed.
The second consecutive night of rioting began early in the evening in Villiers-le-Bel, the northern suburb that saw most of the violence on Sunday.
Police fired tear gas and rubber bullets to keep at bay gangs of youths who were attacking them with stones, fireworks and petrol bombs.
More than 70 vehicles and buildings, including the municipal library, two schools and several shops, were set on fire.
Violence was also reported in four other towns across the Val d'Oise department.
The national secretary of the Synergie police union, Patrice Ribeiro, said at least 77 officers had been injured in the violence and that several had been wounded by shotgun pellets fired at them.
The French Interior Minister, Michele Alliot-Marie, said six police officers had been injured seriously and that they included those who had been "struck in the face and close to the eyes".
Mr Ribeiro said police were facing a situation that was "far worse than that of 2005", which began in the nearby suburb of Clichy-sous-Bois.
"Our colleagues will not allow themselves to be fired upon indefinitely without responding," he told the radio station, RTL.
"They will be placed in situations which will become untenable."
On Sunday, about 30 cars and several buildings, including a police station, were torched in Villiers-le-Bel and neighbouring Arnouville.
Twenty-six police and firefighters were injured and nine people were arrested.
Ms Alliot-Marie said she believed the trouble had been organised and correspondents say the scale of the fury involved suggested the riots might have attracted people from outside the area.
The violence happened despite appeals for calm from the families of the two teenagers of Algerian origin whose deaths sparked the violence on Sunday evening.
A state prosecutor has ordered the National Police General Inspectorate (IGPN) - an oversight body - to carry out a detailed inquiry into the circumstances in which the two teenagers - named only as Moushin, 15, and Larami, 16, lost their lives.
Police sources have said that in Sunday's incident, the motorcycle was going at top speed and was not registered for street use, while the two teenagers were not wearing helmets and had been ignoring traffic rules.
The police car was on a routine patrol and the teenagers were not being chased by police at the time, the officials added. But local youths have said the police car's stoved-in bonnet suggests it rammed the teenagers.
The state prosecutor who ordered the investigation, Marie-Therese de Givry, told LCI television that the teenagers had turned into the path of the police car. She said the officers immediately called emergency services to the scene.
Two witnesses are said to have confirmed this, but the teenagers' relatives and other local residents say the police did nothing to help the dying teenagers.
President Sarkozy said he wanted "everyone to calm down and let the justice system decide who was responsible."
Mr Sarkozy was heavily criticised two years ago after he called for crime-ridden neighbourhoods to be "cleaned with a power hose" and described violent elements as "gangrene" and "rabble".
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