Police were attacked with petrol bombs and stones during disturbances near the Bogside in Derry City last night.
Crowds of youths are believed to have been firing petrol bombs across the city walls at the Memorial Hall on Fahan Street used by Apprentice Boys marchers.
It was the second consecutive night of disturbances in the area, the PSNI said.
The violence flared at around 7.30pm, with order restored just before midnight after talks with community representatives. No injuries were reported but a number of police vehicles were damaged.
Although no arrests were made either, a PSNI spokesman confirmed inquiries were continuing.
