A 5 year old girl and woman in her 30s are in a serious condition following an attack at Parnell Square East this afternoon.
A 5 year old boy and 6-year old girl who suffered "less serious injuries" were taken to Crumlin Children's Hospital for treatment.
The boy has since been discharged.
A man in his 50s is being treated for serious injuries in a Dublin hospital.
Gardaí have described it as a standalone attack, and do not believe the incident is terror related.
Garda Press Officer Liam Geraghty has appealed for anyone with information or footage to contact them.
He's urged the public to let investigators work out exactly what happened, and not to "jump to conclusions."
— Helen McEntee TD (@HMcEntee) November 23, 2023
The Justice Minister has expressed her "deep shock" at the attack.
Helen McEntee says her thoughts are with those injured, especially the children and their families.
The Minister has been briefed on the situation by senior Gardaí.
She says he has "no doubt" the person responsible will be brought to justice.
Diversions are in place on some major routes because of the incident at Parnell Square East.
There are no Green Line Luas services between St. Stephen's Green and Dominick for the moment.
Dublin Bus meanwhile says diversions are in place on Southbound Routes that usually pass the Square.
They will go by Denmark Street, Gardiner Street, Cathal Brugha Street and O'Connell Street before re-joining the ordinary route.
Bus Éireann services 103, 109, 109Z, 111 and NX will be re-directed by Gardiner Street until further notice.