German authorities have arrested five members of a terrorist recruiting network operating on behalf of the so-called Islamic State (IS), local media report.

The arrests on Tuesday morning took place in the states of North Rhine-Westphalia and Lower Saxony. The network recruited and provided logistical support for local volunteers making their way from Germany to Syria.

Among those arrested is an Iraqi citizen known as Abu Walaa, 32, or Ahmad Abdelaziz. The preacher is a leading figure of the Jihadi movement in Germany, and many of his followers have made their way to Syria. Walaa has been at the center of a year- long investigation, which also yielded arrests in the city of Hildesheim in July 2016.

The arrest appears to have been facilitated by a former IS fighter, Anil O., 22, who identified Walaa as Germany’s IS leader.