A man was arrested in connection with starting a late-night house fire in Trondheim, where 11 Norwegians were injured, on Wednesday.
The arson attack occurred in Risvollan, Trondheim, during the early hours of Wednesday morning.
Eleven people were taken to hospital and 44 people were evacuated after the houses started burning in the housing complex at Risvollan in Trondheim.
On the same night, there was a fire at the nearby Sunnland school.
Police are investigating whether both fires could be connected.
Four apartments were completely damaged in the house fire. None of the 11 people who were sent to hospital were seriously injured, police said.
Fire fighters have searched each of the four apartments without finding any people.
When the fire department arrived, the blaze was out of control. Crews focused on preventing the fire from spreading and could not salvage any of the four burning properties.
Police received a call about the fire at 2.13am on Wednesday. At 4.30am, the fire was extinguished.
At 2.51am - around 30 minutes after the fire in Risvollan was reported - local emergency departments received a call about a fire at the Sunnland school at Nidarvoll in Trondheim.
A fire had been started in a shed, and eight people in houses close to the school were evacuated. No one was hurt.