German police detained three people in the western city of Offenbach Tuesday on suspicion of planning a bomb attack on behalf of the ISIS militant group, prosecutors said.
The three suspects wanted to kill as many people as possible in the planned attack in the Rhine-Main region, Frankfurt prosecutor Nadja Niesen said in a statement.
No specific attack targets were yet known but evidence seized from raids of three homes in Offenbach should shed some light, she added.
The main suspect is a 24-year-old German of Macedonian origin who wanted to manufacture explosives and had tried to buy a weapon online. His two accomplices are Turkish nationals aged 22 and 21.
The three suspects are believed to have told people in the past that they identified themselves as ISIS supporters, Niesen said.
Substances that could be used to make explosives and equipment were found at the main suspect's home, she said. The authorities also secured written documents and electronic data.
Niesen said a decision would be made on Wednesday on whether all three suspects or only one would be brought before the investigating judge at a court in Frankfurt.
The judge will decide whether to issue an arrest warrant and order pre-trial detention.