A bomb has exploded near an army base in Northern Ireland housing the headquarters of British intelligence services, MI5.
The incident happened in Holywood, County Down, forcing the evacuation of several homes.
The BBC reports the blast seems to have been timed to coincide with the precise moment that policing and justice powers devolved from London to Northern Ireland.
Police say the device was taken to the barracks on the outskirts of Belfast in a hijacked taxi. There are no reports of any injuries.
Between 50 and 60 people were spending the night in a local community centre, said Basil McCrea, an Ulster Unionist member of the Policing Board.
In March, Northern Ireland Assembly members voted in favour of the transfer of policing and justice powers.
Out of the 105 votes cast in the Assembly, a total of 88 supported the move, with 17 Ulster Unionists voting against, the BBC reports.
Disagreement on the timing of the devolution of the justice powers had threatened to collapse Northern Ireland's power-sharing administration.