French riots: Amiens buildings torched in clashes
Buildings and cars were torched overnight as youths and police clashed in the northern French city of Amiens.
Sixteen police officers were injured in the clashes with up to 100 youths, some of whom threw fireworks, large-sized shot and projectiles, say police.
Reports suggest the unrest may have been triggered after police arrested a man for dangerous driving.
Interior Minister Manuel Valls was jostled when he visited the area.
A small group of people tried to push through his security detail as he walked through the area, alternately booing him, cursing him and trying to speak to him, reported AP news agency.
President Francois Hollande has vowed to beef up security resources to combat the violence, saying public security was "not just a priority but an obligation".
Further police reinforcements have been sent to the zone. The concern is that violence could spread to other suburbs and cities, says the BBC's Christian Fraser in Paris.
A leisure centre, school and vehicles were burned overnight on Monday amid the unrest in the rundown district of Amiens - with some drivers pulled from their cars which were then set alight.
An official estimated damage worth a million euros (£790,000; $1.23m) had been done.
The clashes are believed to have started at about 21:00 (19:00 GMT), ending at about 04:00 once police reinforcements arrived. Up to 150 police officers are said to have used tear gas and rubber bullets to quell the violence.
One police officer was in a serious condition, Mayor Gilles Demailly was quoted as saying. No arrests have yet been made.
The mayor said the clashes left behind a "scene of desolation".
"There have been regular incidents here but it has been years since we've known a night as violent as this with so much damage done," Mr Demailly told Agence France-Presse.
Mr Valls said the violence was "unacceptable", while Mr Hollande said there was "delinquency and criminality that must be foreseen, deterred and punished".
Their stance was echoed by some residents and local workers, who called the violence "disgusting" and spoke of their fear of working in the area.
But one woman told BFMTV she had personal experience of aggressive, heavy-handed policing, and insisted that what occurred was "not gratuitous violence".
"This is violence from anger! We're not animals. We vote and pay our taxes like everyone," said Sabrina Hadji.
This district of Amiens had already been earmarked for extra security spending after 15 trouble spots were named "priority security zones" by the government earlier this month.
There has been a rise in violence in the area in the past month, sparked by the high unemployment and the tensions surrounding police spot checks on residents.
In 2005, the deaths of two teenagers in Clichy near Paris sparked weeks of looting and car-burning in housing estates across France.
It sparked an debate about deprivation and social exclusion, but many analysts say little has changed for France's marginalised youth, many of North African origin.