AMIENS, France (AP) ― Months of tension between police and young people in a troubled district of northern France exploded on Tuesday, with dozens of youths facing off against riot officers in a night of violence. Seventeen officers were injured, a pre-school and public gym were torched, and at least three passing drivers in Amiens were dragged from their cars.

The immediate cause of the riots was unclear, but a standoff between police and people attending a memorial for a young man who died in a motorcycle accident may have been one trigger. Officials underlined that police were not involved in the death.

The eruption of violence shows how little relations have changed between police and youths in France’s housing projects since nationwide riots in 2005 raged unchecked for nearly a month, leaving entire neighborhoods in flames in the far-flung suburbs.

The sister of the young man who died in the accident said it was impossible for people in her community to even speak with the police.

“As soon as they see young people, it’s to handcuff them or harass them,” said Sabrina Hadji, 22. “The dialogue is completely broken.”

Less than two weeks ago, the French government declared Amiens among 15 impoverished zones to receive more money and security, but many people remain frustrated at what they see as official indifference to their situations. Unemployment skews higher in northern France and among the country’s youth.

At the height of the confrontation, 150 officers ― both local and federal riot police ― faced off against young men who fired buckshot and fireworks at them, skirmishing through the neighborhood in the city about 120 kilometers north of Paris. There were no arrests.

“The confrontations were very, very violent,’’ Amiens Mayor Gilles Dumailly told the French television network BFM. Dumailly said tensions had been building for months between police and the impoverished residents, whom he described as “people who are in some difficulty.’’

Anger was still running high when Interior Minister Manuel Valls arrived in the neighborhood Tuesday afternoon. A small group of people tried to push through Valls’ security detail as he walked through the area, alternately booing him, cursing him and trying to speak to him.

One shouted out, “When are you going to speak to us?” before the minister ducked into a building to meet with the mayor, the head of the local prefecture, and Sabrina Hadji and her mother.

Valls, who used to represent an impoverished area outside of Paris in Parliament, showed anger himself, expressing disbelief that police officers had been shot at.

“Shooting a police officer? Burning a school? And then questioning these forces? It’s intolerable,’’ he said at a news conference. “Nothing excuses shooting at police officers and burning public buildings.’’

While he took a tough line in saying that order had to be restored, he added that the residents of the neighborhood are the primary victims and said his door would always be open to them.

Relations between police and youth in housing projects have been troubled for years, perhaps decades. Riots occasionally erupt, often in the hot nights of August, when France’s rich and middle classes head off for long vacations but poor and immigrant families in the projects stay home.

Alain Bauer, a professor of criminology, said circumstances had only worsened since 2005. He said it was hard to predict what would happen after the Amiens violence, which he described as “a culmination of bitterness and tension.”

“These are small events that stand apart unless they take on greater importance,” he said. “It will take an in-depth reaction (from the government), responding to both criminal and social problems.”

The riots usually follow a pattern: Police target a kid speeding on a motorbike or doing something suspicious; the kid speeds or runs away to escape and dies or gets seriously injured in flight. The neighborhood rises up in anger and that night or the next, young people head out to burn cars, police stations or any building representing authority. Police often respond by coming in force with tear gas, further angering the local population.

Hadji, whose 20-year-old brother Nadir died in the motorcycle accident, said the violence was a bubbling up from long-simmering anger. She accused local police of provoking the riots by acting too aggressively when they asked for ID from people gathering at a memorial for her brother.

“The police in Amiens really, really, really hate the people in the northern part of Amiens,” she said. “They consider us to be animals.”

Valls vehemently defended the behavior of police officers when he spoke to reporters, but the local government has asked for an investigation.

The local government said the riot involved about a hundred young men and began around 9 p.m. Monday, ending around 4 a.m. after federal reinforcements arrived. There had been smaller confrontations with police over the past week, including one involving a weekend traffic stop that some local residents thought was unnecessarily heavy-handed.

Until Monday night, the violence in Amiens had been on a smaller scale. By the time the latest confrontation was over, two school buildings had been burned, along with a dozen cars and trash cans used as flaming barricades. At least three bystanders were hurt when rioters yanked them from their cars, the local officials said.

“Public security is not just a priority but an obligation,” French President Francois Hollande said Tuesday, speaking at a memorial for two gendarmes killed in June. “We owe it to the population, we owe it to the security forces.”

In recent days, there has also been unrest in the southern city of Toulouse, where rival groups in two housing projects have been battling for a number of days. The violence marked the first major unrest under Hollande, who took office in May.

Unemployment stands at 12 percent in the Somme, the area in northern France of which Amiens is the governmental seat, compared with 10 percent nationwide. Among French ages 15-24, unemployment stands at 23.3 percent, according to the national statistics agency.