Norwegian police said Thursday they had defused a potentially devastating letter bomb that had been sent to a police station, a rare incident in the tranquil Scandinavian country.The Ski police station, located southeast of Oslo, was evacuated early Wednesday after an employee alerted superiors to a suspicious package.It turned out to contain a homemade bomb primed to explode when the package was opened."A real bomb that could, and was designed to, harm people," police commissioner Steven Hasseldal told reporters."This is a very serious crime. We consider it an attack against the police that could have caused a lot of damage," he said.A bomb disposal unit defused the device.Police said they had no suspects at this stage.This type of incident is extremely rare in Norway, where police are generally respected and where officers are usually unarmed.