(JTA) — Two teenage Muslim girls were arrested for planning a suicide bomb attack on a synagogue in Lyon in east-central France.

The girls, ages 15 and 17, were arrested last week after the plot to blow up the Great Synagogue of Lyon was discovered, the French language JSS News website reported, citing an unnamed source from the Central Directorate of Homeland Intelligence.

The girls never met, communicating only via social media, according to the source.

They were indicted on Aug. 22  for conspiracy to commit terrorism.

“These girls were part of a network of young Islamists who were being monitored by security services,” the source reportedly told JSS News.

The girls are among some 60 people being investigated in France for criminal association in relation with a terrorist enterprise, the Associated Press reported.