An explosion in central Oslo has caused significant disruption this evening, following a controlled detonation of a grenade by police. Authorities have arrested one man in connection with the incident, which has prompted an ongoing investigation.

The blast occurred near the Pilestredet area, close to a university campus, shortly after 9pm. In response to the explosion, police issued a warning to the public, advising them to stay away from windows due to the potential presence of additional explosives in the vicinity.

Residents received alerts on their mobile phones, which stated: "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."

Drones were observed flying over the city centre as police worked to secure the area. Fortunately, no injuries have been reported as a result of the explosion. Authorities continue to assess the situation and investigate the circumstances surrounding the incident.