The group of young men, between the ages of 22 and 36-years-old were wearing masks and carrying weapons. They were dancing to loud rap music, and told police they were busy shooting a music video.
Dortmund police said Wednesday that the weapons were fake.
Police seized two bags of white powder that appeared to be narcotics, but later announced they were just props for the video.
The German rappers were allowed to keep their cameras and film when police found no evidence of illegal activity.
Police said, however, that charges may be filed for violation of German weapons law.