Over 400 gardaí are deployed on foot tonight attempting to restore order as a "lunatic, hooligan faction" caused chaos in Dublin city following a stabbing incident in which five people were injured.
A five-year-old girl is receiving emergency care in hospital following the knife attack, while two children and two adults are also being treated for injuries.
The Luas was set on fire near the Gresham Hotel, while a bus was set alight on O'Connell Street.
Fireworks were set off by rioters who also attacked gardaí.
Specialist units were deployed as gardaí worked to bring the situation under control. A number of shops were also looted.
The Garda Commissioner has condemned attacks on officers and Garda cars.
Drew Harris has appealed to everyone involved in the unrest to "go home" and for people not to listen to misinformation on social media.
Mr Harris said a “complete lunatic, hooligan faction driven by far-right ideology” is behind disorder in Dublin this evening.
“I think there’s disgraceful scenes in terms of a major investigation, the maintenance of a scene and the gathering of evidence,” he told media during a press conference at Mountjoy Garda Station.
“We have a complete lunatic hooligan faction driven by far-right ideology, and also then this disruptive tendency engaged in serious violence.
“We are drafting in resources to deal with that and that will be dealt with properly. I’ve given full direction to our resources here in respect of making arrests and bringing offenders to justice.
“It’s our responsibility to make sure that we police the streets, and part of that is we ask people to act responsibly and not to listen to the misinformation and rumour that is circulating on social media.
“The facts are being established, but the facts are still not clear on a lot of the rumour and the innuendo is being spread for malevolent purposes.”
In a statement, Minister for Justice Helen McEntee said: "The horrific attack today in Dublin city centre was an appalling crime that has shocked us all.
“An Garda Síochána are following a definite line of inquiry and are not looking for anyone else regarding this crime. The perpetrator will be brought to justice.
“However, the scenes we are witnessing this evening in our city centre cannot and will not be tolerated.
“A thuggish and manipulative element must not be allowed use an appalling tragedy to wreak havoc.
“I have spoken to local TDs from all sides of the Dáil and we are of the same view.
“We will not tolerate a small number using an appalling incident to spread division.
“I would appeal for calm in the city centre as An Garda Síochána carry out their work – attacks on members of An Garda Síochána must be utterly condemned and will be dealt with severely.
“I am meeting the Garda Commissioner this evening to discuss the policing plan in the city tonight.
“Most importantly, we must remember the real tragedy of today and allow the investigations take their course.”
President Michael D Higgins has expressed his sympathies for the children injured in the attack on Parnell Square East in Dublin City centre this evening.
In a statement, he said that “all of our thoughts are with each of the children and their families affected by today’s horrific attack”.
“We are particularly thinking of the five-year-old girl and the member of staff caring for her who are both in serious condition in hospital,” he said.
“All of our prayers are with each of them for a full recovery.
“The Gardai deserve all of our support in dealing with this incident.
“This appalling incident is a matter for the Gardai and that it would be used or abused by groups with an agenda that attacks the principle of social inclusion is reprehensible and deserves condemnation by all those who believe in the rule of law and democracy.” - Additional reporting from Press Association
