Nine people were injured when a liquid was poured on an information stand run by the far-right Alternative for Germany (AfD) party in the western German city of Bad Kreuznach, police said on Wednesday.
According to the initial investigation, the liquid was poured from a nearby building towards the party stand, police said.
Several people came into contact with the liquid on Wednesday afternoon and suffered minor skin irritation. Two were taken to hospital as a precaution for further examination but have since been discharged, police said.
Bad Kreuznach is located around 40 kilometres west of Mainz in the state of Rhineland-Palatinate.
Following the incident in the Brückenhäuser area of the town centre, there was a major deployment of police, firefighters and emergency services. A suspect has been identified.
Police said serious injuries were not expected given the small amount of liquid involved.
Investigations into the background to the incident are continuing. A police spokesman said the type of liquid involved had yet to be determined.