Youths assaulted a police station, torched cars and vandalized stores in a weekend rampage that injured 21 police officers in this rundown Paris suburb.

Sunday night's violence, prompted when two teens were killed in a motorbike crash with a police patrol car, was a reminder of unresolved tensions that drove nationwide riots in 2005 in immigrant-heavy housing projects.

Questions remained Monday about the crash in Villiers-le-Bel, a town of public housing blocks home to Arab, black and white residents just a few miles north of the French capital.

Eight people were arrested and 21 police officers were injured — including the town's police chief who was beaten in the face after he tried to negotiate with the rioters, a police official said on condition of anonymity because he was not authorized to speak to the media.

Residents drew parallels with the 2005 riots, which were prompted by the deaths of two teens electrocuted in a power substation while hiding from police in a suburb northeast of Paris.

Violence raged across the nation for three weeks, as youth — 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 French society.

President Nicolas Sarkozy, on a visit to China, 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 scene of the violence Monday afternoon.

Villiers-le-Bel Mayor Didier Vaillant demanded a swift "impartial investigation."

"I ask for a stop to this violence, I ask all residents and especially the youth not to succumb to anger," Vaillant said on RTL radio.

The clashes came hours after the motorcycle crashed into the patrol car. A 15-year-old and 16-year-old were killed in the accident.

Police officials said the motorbike ignored traffic rules and ran into the police vehicle, and that the bike was unregistered and neither teen was wearing a helmet.

The police station was little more than a shell after youths lobbed Molotov cocktails at the building. Few shops in town were spared the violence. About 15 cars were torched, and several fires were set in garbage cans.

Interior Minister Michele Alliot-Marie was heading to the scene.

The head of the opposition Socialist Party, Francois Hollande, called the violence the result of "a social and political crisis."

"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'?"