"A moving bus on fire surrounded by a large crowd could have led to members of the local community being seriously injured".
The focus of the violence, some of it committed by youths in their early teens, was a concrete "peace wall" in west Belfast that separates a British loyalist Protestant neighbourhood from an Irish nationalist Catholic area.
The disorder follows similar attacks on police and riots in Belfast and elsewhere in Northern Ireland in the past week.
The latest violence in Belfast has erupted amid anger from Protestant unionists concerned they're being isolated from the United Kingdom and pushed into a union with the Republic of Ireland due to post-Brexit trade rules.
He added: "The way to resolve differences is through dialogue, not violence or criminality".
"Northern Ireland faces deep political challenges ahead".More news: Police say they're responding to a shooting in Frederick, Maryland
He was joined by Colum Eastwood, the leader of the Socialist Democratic and Labour Party, who told BBC's Radio 4 Today programme that while he was "outraged" by Sinn Fein's behaviour the tensions were also a " direct result of a British Prime Minister who has lied to the unionist people of Northern Ireland".
Police Service of Northern Ireland Assistant Chief Constable Jonathan Roberts said several hundred people gathered on both sides of a gate in the wall, where "crowds ... were committing serious criminal offenses, both attacking police and attacking each other".
Despite the united message, Northern Ireland's politicians are deeply divided, and events on the street are in many cases beyond their control.
The situation in Northern Ireland has been destabilized by Britain's departure from the European Union - after nearly 50 years of membership - that became final on December 31.
Along with the bus being attacked and set on fire, there were clashes between loyalists and nationalists at the peace line street that links the Shankill Road and the Springfield Road, while a press photographer was also assaulted.
He pointed to the role of paramilitary groups who he warned were stoking divisions and exploiting young people within loyalist communities, adding: "It would be wrong to attribute what has happened simply to Brexit and the protocol".More news: AstraZeneca vaccine linked to rare blood clots, says EMA official
A hijacked bus burns on The Shankill Road as protests continue in Belfast, Northern Ireland, on April 7, 2021.
"This is nothing short of child abuse", Ms Long said. But any long-term solution will require political commitment that appears in short supply.
"Those of us who are involved in politics need to make politics work, we need to be able to show that politics can deliver". Sinn Fein and the DUP have blamed one another for the deteriorating situation.
Katy Hayward, a politics professor at Queen's University Belfast and senior fellow of the U.K.in a Changing Europe think-tank, said unionists felt that "the union is very much under threat, that Northern Ireland's place is under threat in the union and they feel betrayed by London".
The tension between the loyalist and nationalist communities is thought to have risen from the decision not to prosecute people who attended the large-scale funeral of a senior republican figure previous year, despite the lockdown restrictions in place at the time.
More than 2,000 mourners attended Storey's funeral on 30 June 2020, and unionists claimed they blatantly ignored social distancing rules at the height of the first wave of the coronavirus pandemic.More news: Biden says higher corporate taxes won't harm USA economy
They called for Northern Ireland's police chief to step down over the matter.