Norwegian police set off a controlled explosion of a "bomb-like device" found in central Oslo yesterday, with a suspect in custody.
A loud bang was reported shortly after the arrival of Oslo's bomb squad.
"The noise from the blast was louder than our explosives themselves would cause," a police spokesman said.
The device had appeared to be capable of causing only a limited amount of damage, the police said earlier.
Police declined to give information about the suspect.
Norway's police security service, PST, said in a tweet it had taken over the investigation from local police.
Oslo's Groenland area, a multi-ethnic neighbourhood, is also where the city's main police station is located, less than 1km away from where the device was found.
In neighbouring Sweden, a truck on Friday ploughed into crowds in Stockholm, killing four people and wounding 15 in what police said was an apparent terror attack.
