Police arrested 16 people during a second night of unrest in Northern Ireland following a violent stabbing in Belfast, a senior minister said Thursday, condemning those involved as engaging in “racist thuggery.”

Clashes with police erupted late Wednesday, hours after a Sudanese man appeared in court charged with attempted murder in connection with a knife attack on Monday night.

Video of the assault, which showed a man straddling another person lying in the street and repeatedly stabbing him, spread widely across social media and fueled anger that spilled into street violence across parts of Northern Ireland.

The victim, Stephen Ogilvie, was in “improving” condition Thursday, Democratic Unionist Party leader Gavin Robinson said after meeting his family.

Ogilvie’s relatives appealed for calm in the wake of the “terrible tragedy,” saying violence was “not welcome.”