LONDON (AP) — Police investigating the killing of journalist Lyra McKee, who was shot dead by paramilitary gunfire in Northern Ireland last month, have made four arrests.

The Police Service of Northern Ireland says males aged 15, 18, 38 and 51 were arrested in Londonderry Thursday under terrorism legislation, in connection with violence in the city the night McKee died.

McKee, who was 29, was killed as she watched rioting in the city, also known as Derry, on April 18.

Dissident paramilitary group the New IRA, which opposes Northern Ireland's peace process, says its members killed her by accident when firing at police.

Three people had earlier been arrested and released without charge.

McKee's death caused wide shock and grief in a region still shaken by tremors from decades of violence.