Over 54 properties in the cities of Frankfurt, Offenbach, Darmstadt and Wiesbaden in the state of Hesse were raided by police early Wednesday morning, according to Frankfurt's state prosecutor.
Approximately 1,100 police officers conducted the raids on apartments, commercial properties and mosques.
Sixteen males were targeted. The only person arrested was the main suspect, a 36-year-old Tunisian man who allegedly worked as a recruiter and trafficker for the Islamic State. He was taken into custody without resistance in Frankfurt.
A spokesman for the state police force said that the suspect also had plans for a terror attack, but these were still in their early stages and a target had not yet been selected.
"With this operation, we are sending a clear message to radical Islamists in Hesse: We have the scene firmly within our sights," Hesse's interior minister, Peter Beuth, said.
On Tuesday evening, three men were arrested during police raids in Berlin on terrorism-related charges. According to a police spokesperson, the arrested individuals are suspected of traveling to war zones in Syria and Iraq and having links to IS. However, there was no indication of concrete plans to carry out an attack in Germany.
The arrested men are supposed to have frequented the same mosque attended by Anis Amri, a 24-year-old Tunisian who murdered 12 people and injured around 50 on December 19 when he drove a truck into a Christmas market on Breitscheidplatz in west Berlin.
The mosque in the Berlin district of Moabit, which is being investigated by authorities, was also searched.