PARIS -- Masked French gendarmes detained a 17-year-old who took a class full of preschoolers hostage Monday, releasing all the children safely after hours of tense negotiations that drew nationwide attention.

Special French intervention police forces (GIPN) and children leave the nursery school Charles Fourier in Besancon, eastern France December 13, 2010 after the children were released after being held hostage. Half a dozen children and their teacher were released safely on Monday after being held hostage for four hours by a teenager armed with two swords at the nursery.  [Photo/Agencies]

"The hostage-taking is over," Jean-Marc Magda, aide to the mayor of the eastern French city of Besancon, told The Associated Press by telephone. All 20 children who had been taken hostage and their teacher were released safely, he said.

The hostage-taker was detained, and remained inside the school with officers from a specialist gendarme force brought in to deal with the situation, Magda said.

French television showed a wide-eyed girl being draped with a green blanket and carried away from the school. Police and worried families had surrounded the school since early in the day.

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The motives of the hostage-taker were unclear.

Besancon Mayor Jean-Louis Fousseret said the teen had been treated for depression but had not taken his medication in recent days. The mayor did not confirm reports that the youth had requested a gun to commit suicide.

The hostage-taker initially seized a class of 20 children but released 14 throughout the morning, including one who "more or less escaped," said Besancon Mayor Jean-Louis Fousseret.

Five or six children and the teacher were believed to be still in the preschool when the officers entered around lunchtime, Fousseret said on i-tele television.

The masked gendarmes pointed their firearms at the school's windows and doors as they entered, in images shown on French TV. They were in contact by telephone with the hostage-taker before the last group of children was released.

Families huddled around the school, with children bundled against the cold. Emergency workers draped a blanket over one woman's shoulders as she wept, in images shown on i-tele television.

The hostage-taker did not threaten the children and allowed them to go to the bathroom throughout the ordeal, Education Minister Luc Chatel said from the scene.

The incident took place at the Charles Fourier preschool in Planoise, a neighborhood of housing projects with a big immigrant population on the western edge of Besancon.

Pupils were still inside the adjacent elementary school while the events unfolded.

"It's a bit traumatizing. ... We are just across from where everything is happening," principal Alain Lietta told the AP. The schools' entrances are about 60 meters (yards) apart. Normally some children go home at lunch but "today, this poses a problem," he said.

He said the children in the elementary school were informed about the situation. "We wanted to give them a maximum of honesty and clarity so as not to scare them."

Education Minister Luc Chatel arrived at the preschool and spoke with the families.

President Nicolas Sarkozy did not comment publicly about the hostage-taking.

Sarkozy first vaulted into France's national consciousness during a similar hostage-taking in 1993 in the posh Paris suburb of Neuilly-sur-Seine, where as mayor he helped free nursery school children and a teacher who had been taken hostage by a masked gunman.