A car bomb exploded early Monday near the headquarters of Britain's MI5 domestic security services in Northern Ireland, police said, adding that there were no reported injuries.
The blast occurred minutes after the devolved power-sharing administration in Belfast resumed control over policing and justice in the province after almost 40 years, in a major step in the peace process in Northern Ireland, AFP reported.
"A device has exploded in a vehicle at the rear of Palace Barracks in Holywood," a police spokeswoman said. The barracks is a former British army complex just outside Belfast which now houses MI5.
The explosion occurred shortly after midnight, she said, adding: "There are no reports of any serious injuries at this stage."
The security services later confirmed the bomb was in a hijacked taxi, which was driven to the rear of the barracks.
The driver then jumped from the car, shouting: "It's a bomb."
The driver's family were held hostage, police sources told Sky News.
Local journalist Brian Rowan told AFP the explosion "shook my front door."
"It appears that the seat of the explosion was on the opposite side of the complex in a layby on Old Holywood Road. The security services have sealed off a stretch of the road covering several miles," he said.
Hundreds of people are employed in the MI5 complex monitoring domestic security across the British-ruled province.
Northern Ireland endured three decades of civil strife between Catholics who wanted the province to become part of the Republic of Ireland and Protestants who wanted to stay within the United Kingdom.
The violence largely ended with the signing of the 1998 Good Friday peace accords, which paved the way for the current power-sharing administration between the Protestant DUP and the Catholic Sinn Fein parties.
The main paramilitary groups including the Irish Republican Army (IRA) have laid down their arms, but sporadic violence still plagues the province, including the killing of two British soldiers and a policeman last year.
Dissident republicans opposed to the peace process are usually blamed.
The policing and justice powers were transferred from London to Belfast at midnight on April 12, resolving one of the most sensitive issues in Northern Ireland.
When lawmakers approved the power transfer deal last month, British Prime Minister Gordon Brown hailed it as the "final end" to decades of conflict.
"The completion of devolution... is the final end to decades of strife. It sends the most powerful message to those who would return to violence: that democracy and tolerance will prevail," Brown said.
The then British government of Conservative prime minister Edward Heath had seized control of policing and justice from Northern Ireland's local ministers in 1972, at the height of the violence known as "The Troubles."
It was a bid to control the worsening security situation, but prompted the fall of the devolved administration and the powers remained with London throughout the conflict, in which more than 3,500 people died.