Residents are told to stay away from windows as armed police rush to the streets

Emergency services have been called to an explosion in the centre of Oslo, police have said.

Police have confirmed that there are still explosives at the site that have not been detonated and that residents should stay away from their windows.

Pictures from the scene on Pilestredet in Oslo, Norway, show armed police have shut off the road, with firefighters understood to be on standby.

Video footage also shows that several police helicopters have been called to the incident.

‘We are working on the basis of a main theory that a hand grenade was planted,’ Olso Police operations manager Øyvind Hammervold told TV2.

The operations manager also confirmed to VG that the bomb squad are at the scene.

Pictures posted on social media by passersby appear to show an undetonated grenade on the street at the scene.

A police statement said: ‘Residents in the area are asked to stay away from windows. Others are asked not to visit the location.

‘There are explosives at the site that have not been detonated.’

Emergency services have been called to an explosion in the centre of Oslo, police have said

Police have confirmed that there are still explosives at the site that have not been detonated and that residents should stay away from their windows

Pictures from the scene on Pilestredet in Oslo, Norway, show armed police have shut off the road

There have been no reports of injuries at the site, located in the immediate vicinity of a university campus and some 500 metres from the royal palace and the Israeli embassy. 

Authorities also sent an emergency message to Oslo residents’ mobile phones, warning them about the blast.

The message read: ‘There has been an explosion in the area (called) Pilestredet. 

‘Given that there is still an explosive device in the area, the police wish that people stay away from windows.’

‘As of now, we are not evacuating the area.’

A previous police statement said: ‘Emergency services are in Pilestredet after an explosion. 

‘The situation is unclear and extensive work is being carried out at the scene.’

Nearby trams have been evacuated, with reports suggesting the wider tram network in the city has been affected.

he incident comes nearly a day after reports of drone sightings near Oslo’s and Copenhagen’s airports 

This is a breaking news story. More to follow.