During a dramatic police operation in Boxberg between Heilbronn and Würzburg, a suspected citizen of the Reich shot at SEK officials.
A police officer was injured - not life-threatening, as a spokeswoman said on Wednesday.
He was probably hit in the leg.
Special forces wanted to examine the building in Baden-Württemberg early in the morning.
Several shots were fired.
The search took place on suspicion of illegal possession of weapons.
A total of seven people were provisionally arrested.
According to dpa information, the man against whom the police action was directed once legally owned at least one weapon.
There was an order from the weapons authority that he had to hand it over.
This injunction should be enforced.
Baden-Württemberg's Interior Minister Thomas Strobl (CDU) said in Stuttgart: "There are indications that the alleged perpetrator is close to or belongs to the Reich Citizens' Scene."
The alleged main perpetrator resisted arrest.
A politically motivated background to the fact cannot be ruled out, the spokeswoman said.
According to the police, the other people were arrested without resistance and unharmed in the property.
A fire broke out.
The building burned down in a controlled manner, it said.
"Reichsbürger" and "Selbstverwalter" deny the existence of the Federal Republic of Germany and its legal system, deny politicians and civil servants their legitimacy and repeatedly break the law.