A bomb partially exploded in Belfast city centre on Sunday night as army bomb disposal experts were examining it, police have said.
The device, left inside a vehicle abandoned in a car park near Musgrave police station and the city's courts, detonated just after midnight.
There were no reports of any injuries.
It is understood the car’s rear windscreen and a door were blown off but the vehicle was not destroyed. No buildings were damaged.
Detective Chief Inspector Karen Baxter told the BBC the bomb was a “viable device which partially exploded”.
Hundreds of people were caught up in the security alert, which was the third to hit Belfast in a day on Sunday.
The vehicle was believed to have been abandoned at about 9.30pm at the street level entrance to an underground car park at Victoria Square shopping centre.
People in the shopping centre, cinema and apartment block were told to leave the area and were offered shelter in the Ulster Hall. Some shoppers, who could not access their cars, also had to spend the night at the hall.
Those caught up in the incident were allowed to return home just after 6am, but six streets in the city centre remained sealed off.
A spokeswoman for the Police Service of Northern Ireland said the security closures were expected to remain in place throughout the morning and would affect the morning rush-hour traffic.
Earlier in the day a small bomb was defused using remotely controlled drone in a residential area of north Belfast.