BOMB SCARE: City on LOCKDOWN after potentially explosive device discovered in Oslo, Norway.

OSLO was placed in lockdown after police revealed a bomb-like device had been discovered in a busy shopping district just a day after the Sweden terror attack.

A number of roads were blocked off after the discovery of a potentially explosive device, police in Oslo told newspaper VG.

Spokesman Svein Arild Jørundland revealed the bomb squad were on the way after officers found a box, around 30cm square, near the bridge in Grønlandsleiret.

Norwegian authorities conducted a controlled explosion of the device, police told reporters.

There were reports of a loud bang shortly after the bomb squad arrived in the capital.

A police spokesman said: "The noise from the blast was louder than our explosives themselves would cause."

He said: "It is of such a size that we do not think it has a great damage potential, but we will have to examine it.

"We have put adequate barriers, so that public safety is safeguarded."

Officers cordoned off the scene and wtnesses reported multiple police cars and ambulances on site.

People were asked to remain behind the cordon and evacuate the normally busy shopping district following the discovery.

Operations manager Marita Aune said a "bomb-like object" had been found and police have "cordoned off a large area".

All restaurants and shops were in lockdown while police swoop in the scene.

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Witnesses are being told to stay inside

Malin Myrvold, 23, and a group of friends had been celebrating a birthday in an apartment just across the walled-off area at the time of the incident.

She said the group have been asked by police to stay indoors, adding: "Everything is blocked off. All restaurants and shops are closed and the street is empty. There are police and ambulance."

"It's really scary. We hope that what they have found is everything, that they can not find more, and that it goes well."

One man is being held in custody and has been brought in to a nearby police station for questioning. 

Social media users have already gone online to express their concern after the discovery.

Rach said: “Stay safe Oslo.”

Mariam added: “I hope everything is ok in Oslo oh my god.”

JOSTEIN MATRE, VG

Huge swathes of road have been cordoned off

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Fire crews and police officers have been called to the shopping district

Loa tweeted: “I hope everyone is safe in Oslo.”

Bri said: “please stay safe if you live in Oslo”

And Maija added: “Hoping the best for Oslo and the whole world.:”

The bomb scare comes just a day after Sweden was rocked by a terror attack in Stockholm, after a stolen truck was driven at pedestrians.

Four people were killed in the attack, and dozens injured.

Eyewitnesses then reported hearing shots and "loud bangs" outside the T-Centralen train station, roughly a five minute walk from the scene of the truck crash.

In the wake of the Swedish attack Norwegian armed police have been deployed to major cities and airports.

Security controls were also stepped up at the border with Sweden.