A police station counter in Hull has been closed after "liquid" was thrown at the front counter wall.
The incident happened some time this morning (Wednesday), at the Clough Road Police Station.
Humberside Police said liquid was thrown at the wall of the enquiry office.
No-one was injured but the force has closed the police station counter "until further notice".
A man is now being held in connection with the incident, police added.
All other enquiry offices remain open as usual.