A bomb that partially exploded inside a car in Belfast city centre contained 60kgs (132lbs) of home-made explosives, police have said.
The alert began at 21:30 GMT on Sunday when a masked gang hijacked a car, placed a bomb on board and ordered the driver to take it to a shopping centre.
It exploded as army bomb experts prepared to examine the car left at the entrance to Victoria Square car park.
There were no reports of injuries. The alert is over and the centre is open.
Detective Chief Inspector Karen Baxter told the BBC it was a "viable device which partially exploded".
"The only people that are going to lose out on this are the general public in the advance to Christmas," said
"We would be looking for anybody with information in relation to that device to come forward."
The police said a silver Renault Laguna car, registration number CJZ 4697 car, had been hijacked in Jamaica Street, in the Ardoyne area of north Belfast.
It was then left at Victoria Square, opposite the city's main police station, and not far from Belfast's court complex.
A security operation began and premises were evacuated. The bomb partly exploded at about 23:15 GMT.
Commuters on Monday face traffic disruption.
Both Victoria Street and Chichester Street were closed overnight but reopened just before 08: 30 GMT on Monday.
Last week, a bus driver was ordered to drive to a police station in Londonderry with a bomb on board.
On Saturday night, a van driver was threatened by two masked men and told to deliver a package to the same police station.
Meanwhile, hundreds of people were caught up in the overnight security alert in Belfast.
People living close to the scene at Victoria Square had to leave their homes overnight, but have now been allowed to return.
Some of those caught up in the alert were moved from a nearby cinema.
Eddie Sheppard, a police officer from County Monaghan, was among 40 people who took shelter at the Ulster Hall overnight.
"We were just coming out and the alarms went off in the shopping centre, so we were more or less told by security staff to vacate or leave the area.
"Our car is parked underground and we are told we can't get out until the morning," he said.
"We've to get back to work in the morning, so it is out of the way a wee bit, but sure what can be done about it, the police are doing their best."
The car, which was located at street level at the top of a ramp to an underground car park, was believed to have been left there at about 21:30 GMT.
BBC NI reporter Rick Faragher, who lives in the Victoria Square apartments, was among those who had to leave their home.
He said at about 22:00 GMT police told him there had been a suspect car and he could not go back inside.
"I had my coat on, my phone with me, but the lights were still on in my flat, they told us to wait outside. They said they were not sure how long it could last for," he said.
"People were confused; they were not quite sure what was going on.
"There was a tremendous sense of frustration, it was particularly cold last night and there was quite a few of us out on the street.
"They let us back in just after five o'clock this morning."
Reproduced under licence from BBC News © 2013 BBC