Armed men burned a hijacked car in Craigavon
Trouble has flared on the streets of County Armagh for a third night.
In Lurgan, hijackers told a woman they had placed a device on her lorry and forced her to drive to a police station. However, nothing was found.
Disturbances are thought to have been sparked last week when three local men were jailed over a dissident republican mortar bomb plot to kill police.
The latest unrest in Craigavon and Lurgan came as police boosted patrols to disrupt dissident republicans.
Police are concerned an attack may be planned for the arrival on Tuesday of new PSNI Chief Constable Matt Baggott.
As a direct response, on Friday evening police launched Operation Dissent which will see more police patrols and checkpoints in parts of Northern Ireland.
In the latest sporadic trouble, two cars were hijacked in the neighbouring towns of Craigavon and Lurgan.
In Craigavon, up to six masked men forced a man out of his car at the Drumbeg roundabout at about 2140 BST on Saturday.
One was carrying a gun while another had a knife.
Twenty minutes later in Lurgan, two men, one armed with a handgun, stopped a woman driving a lorry.
One of the men told her there was a device strapped to her vehicle and told her to drive to Lurgan Police Station.
She drove a short distance before getting out and called police, who examined the lorry but found nothing.
The lorry was hijacked at a railway crossing at Lake Street.
It is the same area where hijacked vehicles were abandoned on the main Belfast to Dublin railway line on Thursday and Friday, disrupting train services.
Last week, a 600lb bomb was defused at Forkhill in south Armagh, a device which police said had been designed to kill its officers.
After the murders of two soldiers and a police officer in March, the threat posed by dissident republicans is said to be higher now than at any time in the past five years.
Vans were set alight on a railway line after being hijacked