Police in Northern Ireland said they had arrested a Sudanese man on Tuesday over a knife attack that left one person in a serious condition and prompted calls online for a protest after footage circulated on social media.
Prime Minister Keir Starmer described the incident as "sickening" after video of the attack, which took place in north Belfast late on Monday evening, was shared widely online.
Police said the suspect was a 30-year-old Sudanese national, correcting an earlier statement that he was believed to be Somali, and cautioned that inaccurate information was circulating online about the victim's condition.
The injured man, in his 40s, remained in a serious condition in hospital, the police said.
It comes at a time of heightened tensions in Britain after the murder of a student who was handcuffed by police as he lay dying from stab wounds after his killer, a Sikh man, falsely alleged a racist attack.
Lawmakers call for transparency on suspect's background
In a debate in the British Parliament in London, some lawmakers called for more transparency about the Belfast suspect's background, saying a lack of confirmed information risked fueling speculation online and stoking tensions over immigration.
Northern Ireland's main political party leaders jointly condemned the attack in a statement, calling it "horrific" and urging calm while backing the police investigation.
The deputy first minister, Emma Little-Pengelly, had described it as a "savage and barbaric attack."
A widely shared post on Facebook and WhatsApp called for protests on Tuesday evening.
"This is a deeply concerning assault and I have declared this a critical incident," Assistant Chief Constable Ryan Henderson said. "We have commenced an investigation to establish a motive."
"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."