Alliance Party deputy leader Eóin Tennyson described the attack in north Belfast as “vile and horrific” and said it had “understandably caused huge distress”.

The assembly member said his immediate thoughts were with the victim and his family and members of the public who intervened.

Tennyson called for “responsible leadership” and that “violence and hate will not be allowed to divide our communities”.

He urged all representatives in the assembly chamber to support the police in their investigations.

Jayne McCormack
BBC News NI political correspondent

Traditional Unionist Voice assembly member Timothy Gaston said Monday's events in north Belfast "can't be divorced from the immigration debate".

He said anyone who attempts to do so is "gaslighting" communities and described the attack as "savage".

Image source, Rebecca Black/PA Wire

Jayne McCormack
BBC News NI political correspondent

Image source, PA Media

Deputy First Minister Emma Little-Pengelly, of the DUP, said people across Northern Ireland were "sickened and appalled" by what had happened.

She said she has spoken to the PSNI Chief Constable Jon Boutcher and Stormont's Justice Minister Naomi Long to reiterate the importance of "clear communication" with the public.

"There can be no excuses and no tolerance for such violence.

"I know emotions are running high - there is anger and concern but I do urge everyone to remain calm to allow the police to carry out their investigation and allow people to establish the full facts."

Little-Pengelly said she had also been in contact with the prime minister to ensure "full and urgent cooperation" with the Home Office to see what information they hold in relation to the man who has been arrested in connection with the attack.

Image source, Rebecca Black/PA Wire

The Alliance Party’s Nuala McAllister, an assembly member for the North Belfast constituency, said it was important that "tensions are not raised" over the knife attack.

“Today is not a day for politics. It is a day for calm,” she said in the assembly chamber.

McAllister also said she would “urge people not to watch the video and allow the police to do their job”.

The assembly member said that “this type of violence doesn't have any place on our streets”.

She also expressed her thanks to the “very brave people” who attempted to intervene.

Brendan Hughes
BBC News NI political reporter

Democratic Unionist Party (DUP) assembly member Brian Kingston said he was “deeply shocked by the barbarity of the attack”.

He commended residents who intervened and police officers who arrived at the scene.

The assembly member, a representative for the North Belfast constituency, urged the Police Service of Northern Ireland (PSNI) to continue to provide “further information” on the incident.

"It is important that we do not have false information circulating online,” he told assembly members.

Police tell us that they are not seeking anyone else at this stage in connection with this crime," he said.

Kingston added: "It is important that factual information is put into the public domain.

"Whatever the circumstances and whether or not that suits everyone's agenda - it is important that we do not have false information circulated online in this era of social media."

Image source, PA Media

First Minister Michelle O'Neill has condemned what she said was a "brutal attack".

She said it was appalling and horrifying and had "deeply shocked" the community.

She said there was no place for violence and her thoughts are with the victim.

O'Neill later commended the courage "of all those who intervened to remove the attacker in advance of police arriving".

Image source, PA Media

The leader of the Ulster Unionist Party (UUP) Jon Burrows tells the assembly: "Like everyone across Northern Ireland I was deeply shocked by the barbaric scenes that we witnessed on social media when a man has been clearly horrifically injured on our streets."

He said his first thoughts were with the victim and he also thanked the members of the public who intervened to save the victim.

The Ulster Unionist Party (UUP) leader also paid tribute to the "swift actions of the police" and the medics who treated the victim.

Burrows, a former police officer, said although there can be "tensions" in our community at times like this, he said political leaders "need to give the police the time and space to do their investigation, to secure evidence and to go through due process".

Image source, Aodhan Roberts

Assistant Chief Constable Ryan Henderson said "officers were on the scene within minutes and the PSNI "wish to acknowledge the members of the public who strived to save the man from further attack".

"Their willingness to step forward to help another person shows incredible bravery and community spirit," he added."We are also aware of footage circulating online and we would strongly urge members of the public not to share or repost these images.

"Doing so risks causing further trauma to the injured man's loved ones and may impact the ongoing investigation.

"Our thoughts remain with the victim's family at this deeply distressing time."

Image source, Rebecca Black/PA Wire

The injured man, aged in his 40s, is in the Royal Victoria Hospital in Belfast where his condition is described as serious.

The Police Service of Northern Ireland (PSNI) said it was "a deeply concerning assault" and they have declared it "a critical incident".

"This brutal attack will have sent shockwaves through the community causing real concern," Ass Ch Cons Ryan Henderson said.

"I want to reassure the local community that we are treating this attack with the utmost seriousness.

"Community safety is our priority and we are currently engaging with local representatives and residents to provide reassurance and support."

The attack is being debated now in the Northern Ireland Assembly.

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Image source, Aodhán Roberts

The Prime Minister, Sir Keir Starmer, has described the attack in Belfast as "sickening" and says he will have "absolutely no tolerance for abhorrent scenes of violence like this on our streets".

One man in his 30s, who police say they believe to be Somalian, remains in custody after the incident on Kinnaird Avenue in north Belfast at about 22:30 BST on Monday.

A video circulating online shows a number of people, including one wielding a hurling stick, confronting the apparent attacker until the police arrived.

Members of the Northern Ireland Assembly are set to to discuss an attempted murder attack in north Belfast.

A man has been arrested over what police described as a "brutal" assault involving a knife, which saw people wrestling the attacker off the victim.

The victim is in a serious condition in hospital, with significant injuries to his face, neck and back.

We'll bring you up to date with the latest and any reaction.