Paris police officials said on Monday that 21 police officers were injured last night in clashes with youths in two Paris suburbs.

Dozens of youths attacked police stations, stores and cars in the northern suburbs of Villiers-le-Bel and Arnouville, after two teenagers of 15 and 16 years old, both of African origin, were killed in an accident. Their motorcycle hit a police car in the suburbs of Villiers-le-Bel, BBC News reports.

According to police, the Villiers-le-Bel police was set on fire and the one in Arnouville was looted. Seven people got arrested.

The clashes lasted for almost six hours.

The violence echoed the riots in November 2005, when three weeks of urban unrest was triggered by the deaths of two teenagers. They were electrocuted at a power station when they were hiding by the police.

Clashes started on Sunday night after the accident occurred.

According to police sources, the two teenagers were driving a stolen motorcycle and that neither of them was wearing a helmet. At the time of the collision with the police car, they were driving at high speed and they failed to cede the right of way to the police cruiser, DPA reports.

Due to collision the front of the car got wrecked and the windscreen was smashed.

On Monday French media reported that the cause of the accident was not determined and an investigation was ongoing. 

After the accident, youths set on fire the police station in Villiers-le-Bel, cars and looted the Arnouville police station.

Riot police tried to suppress the violence, but they way was blocked by youths with burning cars.

In the clashes two police officers were shot and another officer was badly beaten as he tried to calm the mob, said the administration of the departement, or region, of Val- d'Oise.

According to police, between 50 and 100 young people took part in the violence.