The alarm was received on Sunday night. Police, rescue services and an ambulance were called to the scene and the entire building was evacuated.
It is unclear how seriously injured the three are.
"I understand that they have inhaled smoke, but nothing can be completely ruled out," says Mats Öhman of the police.
The incident is being investigated as arson. One of the three people taken to hospital is the person suspected of arson, police say.
We have not received any notification of an arrest, nor any decision from a prosecutor, says Mats Öhman.
He also states that the building is under surveillance while the police conduct a technical investigation.
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