Irish police said five people, including three young children, had been taken to hospital following a serious public order incident in Dublin city centre on Thursday that local media reported as a stabbing.
Police said in a statement that they were following a definite line of inquiry and not looking for any other person at this time.
One girl has sustained serious injuries and the other two children are being treated for less serious injuries, police said. An adult female is also being treated for serious injuries and an adult male has less serious injuries, police added.
Local media reported that the people were stabbed on Dublin's Parnell Square, which is next to Dublin city's main thoroughfare of O'Connell Street. Police said the scene remains sealed off.
The Irish Times reported that the chief suspect has been detained and had sustained wounds believed to be self-inflicted. It said early indications suggested a man tried to attack a number of young people and that passers-by intervened.
The motive for the attack, which occurred close to a school on the street, has not been established, the Irish Times added.