Heavily armoured officers evacuated diners from nearby restaurants to examine the suspicious device, and a man has been arrested.
Police in Norway have detonated an explosive device which was left on a busy commercial street in the centre of Oslo.
A large area was cordoned off following the security alert in the Norwegian capital on Saturday night.
Investigators said the explosive was discovered outside Groenland underground station, and heavily armoured officers swept through the surrounding area to evacuate people from bars and restaurants.
When asked about the controlled explosion, a police spokesman said: “The noise from the blast was louder than our explosives themselves would cause.”
Enquiries are continuing at the scene, but detectives believe the explosive was capable of causing only a limited amount of damage.
One man has been arrested and is being held in custody, but officers have refused to give any further information about the suspect.
The Groenland area is a multi-ethnic neighbourhood which is home to several popular bars and restaurants. Oslo’s main police station lies less than a kilometre away from where the explosive device was found.
Malin Myrvold, who saw the police activity unfold from the fourth floor of a nearby building, said: “Every restaurant was being closed. You could see cops in heavy armour going in every store and restaurant.
“We were trying to see what was going on. The police were screaming at us to get back inside and stay where we were.”
The incident came a day after neighbouring Sweden was hit by a terror attack, when a lorry was driven at shoppers in the capital Stockholm, killing four people and wounding 15 others.
Norway was put on high alert after neighboring Sweden suffered a truck attack in the capital that killed four people and injured 15. The suspect in Friday’s attack, a 39-year-old native of Uzbekistan, has been arrested. It was unclear whether he was also a Swedish citizen or resident or even how long he’d been in the country.
The Norwegian incident happened less than a mile from the government buildings that were damaged in a deadly bomb attack carried out by right wing extremist Anders Breivik in 2011. That bomb and a subsequent gun massacre killed a total of 77 people.