Oslo hit by grenade explosion as residents told 'stay away'One man has been arrested after the incident in the Norwegian capital. View Image One man has been arrested. (Image: NTB/AFP via Getty Images)An explosion rocked central Oslo and brought the cirt to a standstill this evening after a grenade was detonated by police. Drones were spotted flying above Oslo's city centre shortly after 9pm, where a controlled detonation of a grenade was carried out by cops, reports the Mirror. Given that there is still an explosive device in the area, the police wish that people stay away from windows.