A bomb disposal team has been called in Derry after four suspect packages were discovered at locations across the city.
Houses have been evacuated and police have warned of "major disruption" as a result of the devices.
A PSNI spokesman told Mirror Online that officers had been called to four locations in the city.
No further details were available.
A spokesman said: "A number of homes in the area have been evacuated and local diversions are in place.
"There are no further details at this time."
The Northern Ireland police service posted on Twitter: "We‘re dealing with Security Alerts at Iniscarn Road, Harty Court, Strand Road and Moss Park.
"This is going to cause Major Disruption. Houses will be evacuated so please be on hand to help affected family, friends or neighbours. We can only apologise for the inconvenience."
The latest security scares come just three days after 29-year-old journalist Lyra McKee was shot dead during disruption in the city.
A new breed of terrorist is coming through the ranks in Northern Ireland, the detective leading the hunt for her killers said.
Police have arrested two teenagers they suspect are members of the dissident republican New IRA involved in shooting dead the promising young journalist in Londonderry on Thursday night.
Jason O'Toole comment: 'Lyra's killer is not a hero or an Irish patriot'
A gunman aiming to kill police hit the talented 29-year-old in the head. He fired indiscriminately during disturbances in the Creggan estate.
Floral tributes have been piling up at the lamppost where she fell, including one written to "beautiful Lyra" from her partner Sara Canning.
A close friend said her death leaves a void which will never be filled, but she hopes it will bring an end to gun violence in the city and meet the expectations of the victim's peace process generation.
Police Service of Northern Ireland (PSNI) Detective Superintendent Jason Murphy said terrorists are lurking in the shadows, frightening and holding to ransom those they claim to represent.
He said: "What we are seeing is a new breed of terrorist coming through the ranks, and that for me is a very worrying situation."
Lyra McKee shooting: Northern Irish detectives warn of 'new breed of terrorist'
He said there has been a sea-change in community attitudes towards the gunmen, demonstrated in the revulsion expressed by many at Miss McKee's killing.
The New IRA is an amalgam of armed groups opposed to the peace process and it recently claimed responsibility for parcel bombs sent to London and Glasgow in March.
Mr Murphy conceded there remains fear of reprisals for giving information to police from the shadowy gunmen.
He said: "Individuals continue to exert influence over communities, not just in the Creggan but in other parts of the communities as well.
"This intimidation and fear creates a real concern for local residents to come and talk to us as police officers.
"The individuals responsible for Lyra's murder continue to hide in the shadows."
