Northern Irish police said on Wednesday they had arrested four men in relation to the 2019 killing of journalist Lyra McKee in Londonderry, whose death sparked outrage in the British-run province.

The men, aged 19, 20, 21 and 33, were arrested under the Terrorism Act by officers investigating McKee’s murder, police said.

The New IRA, one of a small number of groups that oppose the 1998 peace accord that ended three decades of conflict between opponents and supporters of British rule, said one of its members shot the 29-year-old reporter dead when they opened fire in the direction of police during a riot McKee was watching.

Police charged a 52-year-old man with McKee’s murder last year, while saying more than one person was involved in the crime and the man who had fired the shot that killed her remained at large.