Four people have been arrested over the hijacking and burning of a bus in Newtownards.
The men who are 36, 41, 48 and 55 years of age have been taken to a police station for questioning.
On Monday, November 1, three men boarded a double-decker bus in the Abbot Drive area, forced the driver off and set fire to the vehicle.
They were said to have “muttered something about the protocol”.
The Protestant Action Force, a cover name for the UVF, claimed responsibility saying it was to mark the passing of a deadline set by the DUP to resolve protocol issues.
Searches have also been carried out of four properties in the Newtownards and Bangor areas on Friday morning.
Detective Chief Superintendent Ian Saunders said: “We assess that this incident was carried out by members of a local faction of the UVF.
"Our investigation into this disturbing incident continues alongside an investigation into the more recent hijacking and destruction of a bus in Newtownabbey on Sunday 7th November 2021.
"Both of these violent and destructive attacks have had an impact on those people who were directly involved in the incidents and also the wider community.
"I appeal to anyone with information about either incident, particularly anyone with mobile phone or dashcam footage which they think may help our investigation, to contact detectives on 101.
"Our visible neighbourhood policing presence will continue in key areas."