The fire is not under control and, according to the police, more than 100 homes have been destroyed, Norwegian media report.
No injured residents have been reported, but one firefighter has suffered minor injuries, emergency response leader Lise Bjørnsund told NRK.
The injured firefighter has been taken to hospital.
Bjørnsund says there is also a fire in the surrounding area. Among other things, fire helicopters are involved in the extinguishing work.
Explosions have also been heard in the area in recent times, and the public is being asked to stay away.
At 7:30 p.m., police warned that the fire was spreading south toward another residential area - and residents were urged to evacuate their homes.
A warning message from the authorities states that "there is a risk of explosion and heavy smoke."
The fire department and police were alerted to the fire at 3:30 p.m.
