A married couple who had taken their children with them to join the Daesh terrorist group in Syria are under arrest in Germany. They are accused of being at the center of a network of people planning an attack in Germany, officials said Thursday. The two key suspects are both aged 26 and residents of the western town of Raunheim, according to Frankfurt prosecutors.

They reportedly traveled to Turkey in 2016 and attempted to reach Syria to join Daesh but were arrested by Turkish authorities and sent back to Germany.

A series of raids early yesterday focused on the couple as well as about a dozen others aged between 22 and 32, most of them with either German or German-Moroccan citizenship. Investigators say there was reason to believe they were preparing a major attack. Those arrested also stand accused of trying to assist others who hoped to reach Syria to fight. About 200 officers involved in the case participated in the search of 15 residences in the towns of Biebesheim, Kerpen, Raunheim and Ruesselsheim. They confiscated tens of thousands of euros, as well as papers and digital documents.