The violence Sunday night was prompted by a crash in which two teens on a motorbike were killed in a crash with a police patrol car. It served as a reminder that tensions which drove nationwide riots in 2005 in predominantly immigrant housing projects remain unresolved.
Questions swirled Monday around the circumstances of the crash in Villiers-le-Bel. The town, in Paris' northern suburbs, has many public housing blocks and is home to a mix of Arab, black and white residents.
Residents said the officers involved in the accident left soon afterward, leaving the stricken teens behind.
The internal police oversight agency opened an inquiry into possible manslaughter and non-assistance to people in danger, a police official said on condition of anonymity because he was not authorized to speak to the media.
President Nicolas Sarkozy, in China on a visit, urged calm.
"I want everyone to calm down and let the justice system determine who was responsible," he said.
Interior Minister Michele Alliot-Marie visited the site of the violence Monday afternoon.
Tension was palpable Monday as sanitation workers swept broken glass and other debris off the streets of Villiers-le-Bel. Many people predicted more violence after nightfall.
In Sunday's violence, eight people were arrested and 21 police officers were injured including the town's police chief, who was beaten in the face when he tried to negotiate with the rioters, a police official said.
Residents drew parallels with the 2005 riots. That unrest was prompted by the deaths of two teens electrocuted in a power substation while hiding from police in a suburb northeast of Paris.
In 2005, the backlash against police spread across the nation and raged for three weeks. Youths, many of them black or of Arab origin, torched cars and clashed with police in an explosion of anger over discrimination, unemployment and alienation from mainstream society.
Those riots called the government's attention to problems that had been festering for decades. A recent study by the state auditor's office showed that money spent in recent decades has done little to solve those problems.
Didier Vaillant, the mayor of Villiers-le-Bel, called for calm Monday and demanded an "impartial investigation" as quickly as possible.
"I ask for a stop to this violence, I ask all residents and especially the youth not to succumb to anger," he said on RTL radio.
But police officers appeared to be bracing for more violence after nightfall.
Sunday's nights clashes came hours after the motorbike crashed into a patrol car. The driver and passenger, aged 15 and 16, were both killed.
Rumors circulated that officers had been responsible for the crash. Police officials said the motorbike ignored traffic rules and ran into the patrol car, that the bike was unregistered, and that neither teen was wearing a helmet.
In ensuing clashes, witnesses said, police fired rubber pellets at rampaging youths. Later, shots were fired at officers in the police station, and reinforcements were called in.
Little more than the shell of the police station remained, after youths lobbed Molotov cocktails at it. Few shops were spared in the violence, which left a McDonald's burned, among other businesses. About 15 cars were torched, and several fires were set in garbage cans.
The head of the opposition Socialist Party, Francois Hollande, called the violence the result of "a social and political crisis" and lamented the "climate of suspicion, of hate, that can exist in many neighborhoods."
"Promises were made. We want to see the results," Hollande said on France-Inter radio of government promises to address suburban tensions. "How long have we been talking about a 'plan for the suburbs?"'