Detectives from the PSNI investigating the murder of Lyra Mckee last month have arrested four people.
The 29-year-old journalist was shot while watching disturbances in Derry last month.
Dissident republican group the New IRA said its members carried out the killing.
Four males aged 15, 18, 38 and 51 were arrested under Terrorism legislation in Derry city this morning in connection with the violence.
They have been taken to the Serious Crime Suite in Musgrave Station, Belfast where they are currently being questioned by detectives.
Ms McKee was killed on April 18 following violent disorder in Creggan.
"As part of this morning’s operation detectives carried out searches at four houses in the city and arrested four people in connection with the violence which was orchestrated on the streets of Creggan on the evening of Lyra McKee’s murder," said Detective Superintendent Jason Murphy, the senior detective leading the investigation
"They are currently in custody where they are being questioned."
Detectives from the PSNI’s Major Investigation Team investigating the murder of Lyra Mckee following violent disorder in Creggan in Derry/Londonderry on 18th April have arrested four people under Terrorism legislation. For more info see link below -https://t.co/8Sw3xmYwRu— Police Derry City and Strabane (@PSNIDCSDistrict) May 9, 2019
Detective Superintendent Murphy called once more for witnesses to come forward and share footage if available.
"I want to thank the public for the widespread support we have received to date, including more than 140 people who have provided images, footage and other details via our dedicated Major Incident Public Portal.
"I still want to hear from anyone who can tell us anything they know. I would urge anyone who has any information to contact my team of detectives on 101.
"Alternatively, if you would prefer to provide information without giving your details, you can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111."