Gardaí are investigating two incidents involving groups of young people in Howth and Kilbarrack in which two teenagers were injured.
A 16-year-old boy was assaulted at the East Pier in Howth this afternoon and is understood to have fallen on to the rocks.
A large group of young people had gathered there and gardaí dispersed the crowd at around 4.45pm.
The injured teen was treated at the scene and was taken by ambulance to Beaumont Hospital.
His injuries are not thought to be life threatening.
Less than an hour later, a 14-year-old boy sustained a head injury during an incident involving a large group of teens at Kilbarrack Dart station.
According to gardaí, some youths also attacked ambulance personnel as they attempted to treat the injured boy as well as gardaí who intervened to disperse the group.
Two boys, in their mid-teens, were arrested at the scene for alleged public order offences.
The injured boy did not need to go to hospital for treatment.
Anyone with information about either incident is asked to contact Raheny Garda Station on 01 6664300 or the Garda Confidential Line on 1800 666 111.