Five police officers were injured, with one requiring hospital treatment, following public disorder at a park in Co Down.
The PSNI said officers were attacked with missiles after they had attended reports of anti-social disorder at Crawfordsburn Country Park where approximately 600 young people had gathered on Wednesday.
Police in Ards and North Down have arrested two teenagers.
Chief Inspector McGrattan said: “Our officers were in attendance at the country park following a report of anti-social behaviour at approximately 7.15pm.
“Up to 600 young people had gathered.
“Unfortunately, when officers were carrying out their duties, items were thrown in their direction and missiles also thrown at police vehicles from the crowd.
“A 17-year-old girl was arrested on suspicion of disorderly behaviour, resisting arrest and assault on police.
“She has since been released pending a report to the Public Prosecution Service (PPS).
“A 16-year-old man was arrested on suspicion of resisting arrest, disorderly behaviour, assault on police and obstructing police. He remains in custody at time.
“Five officers sustained injuries as they tried to bring the crowd under control, with one requiring hospital treatment as she had received lacerations to her hand and a possible broken finger.”
Mr McGrattan added: “With the hot weather set to continue over the coming days, we are asking all visitors to respect the local area and take personal responsibility for their behaviour.
“Our message extends to parents also, do you know where your young people are, who they are with and what they are doing?
“We want to reassure the community that local police will be proactively patrolling these areas, keeping a visible presence and anyone breaking the law will be identified and robustly dealt with accordingly.
“I would encourage anyone who witnesses any anti-social or criminal behaviour to report any such incidents to us on the non-emergency number 101.”