Three significant security alerts in Londonderry that came in the wake of a car bombing have been condemned by police as "deliberate and anti-community" hoaxes.
Residents were forced to leave their homes in the vicinity of the incidents on Monday, two of which involved masked men hijacking vehicles, while bomb disposal experts carried out checks.
The alerts ratcheted up tensions already running high in the city following a car bombing on Saturday that police believe was carried out by dissident republicans.
PSNI District Commander Superintendent Gordon McCalmont said the impact on the communities from the scares could not be underestimated and the force shared their "anger and frustration".
"The occupants of the hijacked vehicles did not believe when they set out for work this morning that they would be threatened by masked men," he said in a statement.
"We are grateful to those in the community who worked with us to find temporary shelter for those evacuated and for the patience of the people of this city as we worked as quickly as possible to make sure it was safe for normal life to resume.
"We share your anger and frustration when incidents like this happen but our overriding priority will always be the safety of everyone in this city."
Alliance Party leader Naomi Long earlier condemned the "despicable bunch of thugs" behind the hoaxes.
"These people have no respect for the city or its people," she wrote on Twitter.
In the first scare on Monday three men reportedly hijacked a white Transit van in the Circular Road area at around 11.30am before throwing an object in the back and abandoning the vehicle.
Army bomb disposal experts carried out a controlled explosion on the van.
Just over two hours later, at 1.45pm, police received a report that four masked men - one allegedly armed with a gun - had hijacked a postal delivery van on Southway.
Police said the two occupants of the van were ordered to drive to Lonemoor Road and leave it there.
The third incident saw another abandoned vehicle in the city cause panic on Monday night.
Police attended Northland Road after an Asda delivery van was left parked across the road, stopping traffic in front of St Mary's secondary school.
Elderly residents were evacuated from their homes in pyjamas as police attempted to secure the area.
It comes after a dissident republican group styling itself as the New IRA was blamed for the bombing outside Bishop Street court on Saturday.
Dramatic CCTV footage of the incident released by police showed a group of people walking past the car containing the bomb minutes before the explosion.
Four men arrested over the blast were released unconditionally on Monday.
Meanwhile a 50-year-old man remains in police custody for questioning over an armed robbery in the city last Tuesday.
Some believe the timing of Saturday's bombing may have been linked to a symbolic anniversary in the history of militant republicanism, as it came ahead of the centenary of the outbreak of Ireland's War of Independence in 1919.
The Brexit debate has prompted claim and counter-claim about whether the imposition of a hard border in Ireland will lead to an upsurge in dissident republican attacks.
The Irish Government has warned of the prospect of an increase in violence if physical infrastructure is installed on the border, but the DUP has dismissed it as scaremongering.
On Monday afternoon, Northern Ireland Secretary Karen Bradley told MPs the weekend bomb blast, which caused no injuries, had "absolutely nothing to do with Brexit".
DUP Westminster leader Nigel Dodds welcomed Ms Bradley's assertion that the bomb was unrelated to the Brexit debate, adding it is also "somewhat unrelated" to Stormont's collapse.