A number of PSNI officers have been injured during disorder in the Nailors Row area of Co Derry.
Petrol bombs, fireworks and heavy masonry were thrown at officers, according to the PSNI.
It said that it is working with community representatives to "prevent further escalation" as the unrest is "presenting a serious risk to the safety" of residents.
The PSNI urged parents and guardians to "bring their children home".
Earlier, it reported "sporadic disorder" in the locality and asked people to avoid the area.
