Emergency services are responding to an explosion that occurred Tuesday evening in the Pilestredet area of central Oslo, police said.
The blast happened near Parkveien around 8:44 p.m. local time, prompting a large-scale emergency response, according to Operations Leader Vidar Pedersen.
"Emergency services are in Pilestredet following an explosion. The situation is unclear and we are working broadly at the scene," Pedersen said in a statement to the press.
The extent of any damage or injuries remains unknown, police said.
The Oslo Fire and Rescue Service dispatched three vehicles to assist police at the scene, according to Watch Commander Arvid Nordstrand at the fire department's emergency control center.
Police have expanded security cordons around the area as the investigation continues, Norwegian news agency NTB reported.
Pilestredet is located in Oslo's city center, near several government buildings and educational institutions. The cause of the explosion has not been determined.