In a dispute in front of a pub in Mannheim, six men between the ages of 35 and 45 were shot injured.
They were taken to surrounding clinics, the prosecutor and police announced on Saturday.
A first clue led the investigators into the rocker milieu.
An investigation team of 20 officers with the code name "Jakob" was set up at the Mannheim Criminal Police Office.
After the fact, at least one stranger fled the scene in a dark car, the authorities said.
A manhunt was initially unsuccessful.
The background to the crime was initially unknown.
The act may be related to a rocker group.
This will be further determined.
During the act, a motorcycle typical of the rocker scene was standing in front of the bar, it was said.
If there is any news, it should be communicated on Monday, explained the Mannheim police over the weekend.
The dispute in Waldhof started on Saturday night around midnight.
According to the information, the injured men all have German citizenship and are not in mortal danger.
It was initially unclear whether one or more perpetrators fired the shots, as a police spokesman said.
The forces in Mannheim are supported by experts from the Forensic Institute at the Baden-Württemberg State Criminal Police Office (LKA) in securing and evaluating traces.