Unknown perpetrators sprayed a total of 28 traffic signs with paint on a street in Lünen, rendering them unusable.
As the police announced on Tuesday, the rioters apparently struck the night before.
"Under criminal law, there is suspicion of damage to property that is harmful to the community," said the investigators.
For this they face up to three years imprisonment.
Lünen - The police are now looking for witnesses.
dpa