Rioting youths opened fire on police and set dozens of vehicles ablaze in a seventh night of violence in Paris.
In escalating unrest, shots were fired at police and firefighters, while gangs besieged a police station, set fire to a car showroom and threw petrol bombs.
At least 15 people were arrested and nine injured across north-east Paris.
France's government is facing mounting criticism of its handling of the riots, triggered by the deaths last week of two teenagers of African origin.
Bouna Traore, aged 15 and Zyed Benna, 17, were electrocuted at an electricity sub-station. Local people say they were fleeing police during a disturbance, a claim the authorities deny.
Interior Minister Nicolas Sarkozy met with the boys' families on Thursday, as a criminal investigation and an internal police inquiry into their deaths were opened.
French Prime Minister Dominique de Villepin and Mr Sarkozy cancelled overseas trips to hold a crisis meeting in the face of the growing dissatisfaction with the government's failure to quell the violence.
Both men are likely rivals for the presidency in 2007, and their different approaches to the rioting has split the cabinet.
Mr Sarkozy has caused controversy by labelling the rioters as "rabble" and saying many of the suburbs need "industrial cleaning", but Mr de Villepin has preached a more conciliatory message, urging ministers not to "stigmatise" vast areas.
Wednesday night's violence erupted in 10 areas across the Paris department of Seine-Saint-Denis, home to poor, largely immigrant communities with high levels of unemployment.
Locals officials said rioters set fire to 177 vehicles across the region. In the flashpoint town of Aulnay-sous-Bois, youths set fire to a car showroom and damaged two primary schools, a post office and a shopping centre
Two live rounds were fired in the town of La Corneueve, and fire fighters in Saint-Denis and Noisy-le-Sec were also shot at, a senior local official said.
There was violence in another northern area, Le Blanc Mesnil, where a French TV truck was overturned and burned. In the western Hauts-de-Seine department, a police station was bombarded with petrol bombs, the AFP news agency reported.
The situation also remained tense in Clichy-sous-Bois, where the teenagers died, and where the rioting first broke out.
In recent days there have also been incidents involving groups of youths in other departments near Paris, including the Val-d'Oise, Seine-et-Marne and Yvelines.
Police said they made more than a dozen arrests overnight.
Francois Masanet, secretary general of the French police union, described the situation as "dramatic", and warned that the violence could escalate.
Many youths in the suburbs feel alienated from French society
French politicians are facing up to the reality that many of the mainly immigrant populations in cities have long been in a state of chronic tension, says the BBC's European Affairs correspondent William Horsley.
Immigrants and their offspring make up 10% of France's population, but many are without French citizenship and the right to vote. They also suffer the highest rate of unemployment, and their relations with the police are generally difficult or hostile, our correspondent says.
Dalil Boubakeur, the head of the Paris mosque and the president of the French Council for the Muslim Religion, said living conditions for Muslim immigrants in the suburbs were unacceptable.
They "must be given the conditions to live with dignity as human beings", not in "disgraceful squats".
Clichy-sous-Bois: Two teenagers die in electricity sub-station on 27 October. Successive nights of rioting follow rumours they were fleeing by police. A number of people arrested or injured.
Aulnay-sous-Bois: A flashpoint after violence spread from Clichy. Shots fired at police and cars and shops set ablaze. Further trouble in eight nearby suburbs, with more shots fired at police.
Others: Police report incidents involving gangs of youths in town in the suburban departments of the Val-d'Oise, Seine-et-Marne and Yvelines. Reports of petrol bombs thrown at a police station in the Hauts-de-Seine.