Ten police officers have been injured during disorder in Derry on Saturday,.
The PSNI said fireworks, petrol bombs and other missiles were used to attack police.
Derry City & Strabane Superintendent William Calderwood said one person has been arrested.
“The scenes we witnessed were disgusting, and I want to commend our officers for their professionalism,” he said.
“These were difficult conditions for officers from across numerous departments. To see our officers injured as a result of this violence is appalling. It is completely unacceptable.
“To date one arrest has been made, but we can reassure you a robust investigation is underway to bring all those responsible for this violence to justice.”
Mr Calderwood called the scenes of disorder “disgraceful and senseless”.
“I want to make it clear this violence involved individuals who were intent on attacking police, and who exploited an increased police presence in the city yesterday to do just that,” he said.
“We know from the work our officers do on a daily basis that last night’s disgraceful and senseless violence will have provoked anger in the local community and wider area.
“The public can be reassured you will see our officers on duty today, continuing to work with communities, and working to keep people safe.”
Secretary of State Hilary Benn posted on X, formerly known as Twitter: “I’m appalled at the attacks on police in Derry/Londonderry last night.
“My thanks to the PSNI for working to keep people safe and our thoughts are with the officers who were injured.”
