President Nicolas Sarkozy, visiting China, appealed for calm on Monday, while police braced for more problems. With several dozen officers injured during two nights of rioting, the violence was a reminder of the tensions that drove weeks of rioting in 2005 in poor neighborhoods with large minority populations.
Anger focused on police, with residents claiming that officers left the scene of Sunday's crash without helping the two teens whose motorbike collided with their car. Officials cast doubt on the claim but the internal police oversight agency was investigating nevertheless.
Investigators were still trying to piece together exactly what happened in the Sunday afternoon crash in Villiers-le-Bel, a town of public housing blocks home to a mix of Arab, black and white residents in the French capital's northern suburbs.
Police officials said the motorbike ignored traffic rules and crashed into the police vehicle, and that the bike was unregistered and thus not authorized for use on French roads. Neither of the teens - aged 15 and 16 - was wearing a helmet, and the prosecutor's office said the bike was going at maximum speed.
The internal police oversight agency opened an inquiry into whether the deaths were manslaughter and whether the officers failed to help the teens, a police official said, speaking on condition of anonymity because he was not authorized to speak to the media.
An alcohol test showed that neither of the officers had been drinking, and initial inquiries suggested they did not appear to have caused the crash, police said. The prosecutor, Marie-Therese de Givry, told LCI television that the officers called rescue services to the scene.
Villiers-le-Bel was on edge Monday for a second night, though the families of the two teenagers called for calm. A crowd of youths set police barricades on fire and threw stones and Molotov cocktails at officers, who retaliated with tear gas and rubber bullets. In Villiers-le-Bel and surrounding areas, youths set fire to 36 vehicles, the area's prefecture said.
Youths were seen firing buckshot at police and reporters. A police union official said 38 officers were wounded, including three seriously - one of whom had a shoulder wound after a shot from a hunting rifle pierced his bullet-proof vest. One reporter also was injured.
Two youths were taken into custody, the prefecture said. Among the buildings targeted by the youths was a library that was set afire.
"The situation is tense; there are a lot of police on the ground to prevent more flare-ups," said Gaelle James of the Synergie police officers' union.
In Sunday's violence, eight people were arrested and 20 police officers were injured - including the town's police chief, who was beaten in the face when he tried to negotiate with the rioters, police said. One firefighter also was injured.
Also Sunday, witnesses said, police fired rubber pellets at youths. Two police stations were targeted, one with Molotov cocktails. A McDonald's restaurant was burned, as were about 15 cars and several garbage cans.
Sarkozy said: "I want everyone to calm down and let the justice system determine who was responsible."