An Illegal Koranic school teaching up to 20 children as young as six was discovered inside a mosque, earlier attended by several extremists, in a Paris suburb. French prosecutors believe the children were at risk of being “turned into jihadist recruits.”

The ‘Little Bees School’ was found during a police raid in Al-Islah mosque in Villiers-sur-Marne commune in Paris eastern suburbs on Wednesday. Some 40 police officers were involved in the operation, French media reported.

It was organizing Koran classes for some 15-20 children between six and 12 years old, Le Parisien newspaper reported. The classes were held for some two years.

“The investigation has confirmed the existence of a Koranic school, which was illegally teaching students and where [children] were at risk of indoctrination,” the French interior minister said in a statement.

At least three people have been arrested in connection to the case, including the imam of the mosque, the ministry added, calling to “fight radical Islamism by all legal means.”

The children were in danger of “being turned into jihadist recruits,” local prosecutors said, as cited by The Local.

Saïd Merabet, a spokesperson for the Al-Islah mosque claimed that the mosque didn’t know about anything illegal happening during classes.

“We rented the school a big room on the first floor, but we were under the impression that everything was in order; three or four teachers took turns to teach class,” he said. “We’re low on funds. Renting out that classroom allowed us to pay the mosque’s electricity bill.”

He added that “people speak a lot of nonsense about” Al-Islah mosque, which is “demoralizing.”

“We’re not radical Islamists. Every Friday, our imam preaches about the need to fight extremism.”

In April, some 12 people have been sentenced to up to 10 years in prison for radicalization. They were all attendees of Al-Islah mosque. Among them was a 27-year-old mother, who had traveled with her three children to Syria to join her husband.

Villiers-sur-Marne commune was also a place of residence of Hayat Boumeddiene, a fugitive and a suspected accomplice of Amedy Coulibaly who killed four hostages in the kosher store and a police woman in Paris in January 2015.

France has been on high alert following a series of Islamic State (IS, formerly ISIS/ISIL)-linked attacks since January 2015. The largest loss of life came in November 2015 when at least 130 people were killed in Paris. Following that attack, France introduced a state of emergency, which is ongoing.

A tragedy in Nice on July 14 of this year killed at least 84 people when a truck driven by an IS sympathizer plowed through a crowd during Bastille Day celebrations.

Later that month, France was shaken by the murder of Father Jacques Hamel in Saint-Etienne-du-Rouvray, northern France, by two purported IS militants. The 85-year-old was killed when his throat was slit during a hostage situation at the local church. French police killed the IS-inspired attackers, Adel Kermiche and Abdel Malik Petitjean, both 19, as they tried to flee the church.