The arrests were made after some 200 police officers carried out raids in the states of Hesse and Rhineland-Palatinate.
The men had plotted to "kill as many 'non-believers' as possible" using a vehicle and guns, prosecutors said.
A 21-year-old man from Offenbach, near Frankfurt, and two 31-year-old brothers from Wiesbaden are the main suspects.
"They had already made contact with different arms dealers, rented a large vehicle and collected financial assets to use for the purchase of guns and the execution of the planned murders," a spokeswoman for the prosecutor's office said.
The suspects are aged between 20 and 42 and several are German nationals, the spokeswoman added.
https://www.bbc.com/news/world-europe-47677657
I can see Muslim extremists attacking America, we're basically at war with them. But I can't figure out why they would want to attack Germany.
Why do you think Muslims want to attack Germany?