Police said the three children, a man and a woman were taken to hospitals around Dublin shortly after 1.30pm.

One of the children, a girl, and the woman are being treated for serious injuries.

The other two children and the man are being treated for less serious injuries, according to police.

Irish Prime Minister Leo Varadkar said a suspect has been detained. Earlier, police said they are not looking for anyone else at this time.

The scene at Parnell Square East remains sealed off and police were being assisted by other emergency services.

Stephen Murphy, Sky News' Ireland correspondent, said witnesses have told police they saw a man, who was reportedly wielding a knife, "attack several young people" as they left school.

The school is an Irish-speaking primary school where all students would do lessons in Irish.

"It appears that bystanders and eyewitnesses have played a huge role in bringing this incident to a halt," Murphy said.

"Witnesses have spoken of seeing several bystanders become involved to try and intervene and restrain this man."

He described Parnell Square as an extremely busy area "right in the heart of Dublin city".

"Five casualties have been taken to various hospitals in the Dublin region," an Irish police spokesperson said.

"An Garda Siochana is in contact with parents of all three injured children."

Read more from Sky News:
Large fire breaks out at high-rise building in Reading
Director of al Shifa hospital in Gaza City arrested

Mary Lou McDonald, leader of Ireland's opposition party Sinn Fein and a representative of Dublin Central, told Sky News: "The community is numbed and horrified.

"This is the last thing you expect to happen on a Thursday afternoon in the middle of Dublin city.

"It's a great school community and people's hearts are with the children who have been traumatised and those who have been injured.

"There aren't actually words to describe how numbed people feel. This doesn't happen in our city at a school as very young people are being collected.

"We pray for their full recovery, and for the parents."

In a post on social media website X, Ms Mcdonald also named the school affected as Gael Cholaiste Mhuire.

Helen McEntee, Irish justice minister, said she was "deeply shocked" by the "appalling attack on three innocent children and a woman".

"All our thoughts are with those injured, especially with the children, their parents and families, during this extremely difficult period," she said.