Three young children and a woman in her 30s were injured near a school in Dublin on Thursday, the police said, an attack that was followed by destructive riots that they blamed on the far right weaponising “misinformation” about the episode.

An adult woman in her 30s and a 5-year-old girl sustained serious wounds in the attack, in which a knife was used, police said, while a 5-year-old boy and a 6-year-old girl were being treated for less serious injuries. The boy was later released from hospital.

A suspect in the case was in custody, according to the Garda Síochána, the Irish police force. Drew Harris, the Garda police commissioner, said the motive for the attack remained “entirely unclear”. The attack, which police described as “a serious public order incident”, took place at Parnell Square East, in central Dublin, shortly after 1:30 pm (local time) on Thursday.

That evening, violent scenes broke out in the city after a group of rioters attacked police vehicles and set fires. Videos from the scene showed stores being looted, police cars and public buses aflame, and people clashing with police officers.

In the wake of the attack, far-Right figures spread rumours online about the nationality of the attacker, and the news service AFP said that one protester told them that “Irish people are being attacked by these scum”.

The police said the suspect in custody was a man in his late 40s or early 50s, who was also injured, but they did not give further information about him. They blamed a far-Rright faction for the disorder on Thursday and asked people to leave the streets.

Harris said the riots were “disgraceful”, and suggested they were driven by misinformation about the knife attack that was being spread online for “malevolent purposes”.

Liam Geraghty, a police spokesperson, said at a news conference that preliminary information suggested the knife attack was a stand-alone event and not an act of terrorism. He added that investigators were following a definite line of inquiry and were not looking for other suspects. The police said it was keeping “an open mind at this early stage of the investigation”.

“An attack on children is an act of absolute cowardice and depravity,” Gary Gannon, an MP for the area, wrote in a statement.

New York Times News Service