Four men have been arrested as part of the investigation into the murder of journalist Lyra McKee in Derry in 2019.
The men, aged 19, 20, 21 and 33, were arrested in the Derry area this morning under the Terrorism Act.
They are being held at the Serious Crime Suite at Musgrave Police Station.
Ms McKee was shot dead during rioting in the Creggan area of Derry on 18 April 2019.
PSNI Detective Superintendent Jason Murphy said: "These arrests are the culmination of a detailed two-year investigation into Lyra's murder and the events which preceded it.
"The local community have supported the Police Service of Northern Ireland throughout the course of this protracted investigation and I wish to thank them for their continued support and patience whilst this phase of the investigation is ongoing."
One man, Paul McIntyre, 53, from Kinnego Park in Derry, has already been charged with Ms McKee's murder.
Another man has been charged with rioting and other offences related to the events of the night in Creggan.