The alarm came in at 00:10 on Wednesday night. When police arrived at the scene, the fire was fully developed and had spread.
Initially, it was unclear whether anyone was in the apartments.
"We don't know if anyone is left in the homes. The fire has spread to several apartments," said Anders Wennegren, duty officer at police in Region West.
Later that night, police said there were no reports of anyone being injured.
Police have launched a preliminary investigation into arson, and a person in his 50s has been arrested on suspicion of the case.
