The small regional commuter aircraft was carrying 12 passengers and four crew when it skidded off the runway and caught fire after landing at Stord airport, police said.
John Olav Olsen, a police officer, said: "I can confirm that three persons have been found dead in the plane."
Police said 13 people were rescued from the wreckage. All were sent to hospital for treatment and three were flown to a severe burn centre in Bergen, about 60km away.
They were unable to further details or the nationalities of the casualties.
The flight was on its way from Stavanger, in southwestern Norway, to Molde in western Norway after a stopover in Stord.
It had been chartered by oil services group Aker Kvaerner.
Torbjoern Andersen, an Aker Kvaerner spokesman, said that all the passengers on board were flying out to work on the Ormen Lange gas field.
Public broadcaster NRK aired voices of witnesses describing a loud boom, a fireball and billowing smoke.
Pictures from the site showing a huge smoke chimney above burning debris.