The victim was found by police in a serious condition after being alerted to an incident at an apartment in Karlskrona. She was immediately rushed to Blekinge hospital where she was pronounced dead.
A 31-year-old man and a 30-year old woman were arrested during the early hours of Thursday morning. Police are currently holding the pair on suspicion of probable cause.
The suspects are not the girl's parents but police disclosed that they had a "certain relationship" with the victim.
"They are not her parents. Her parents have not been informed and are abroad," Lotta Hansson of the Blekinge police told the TT news agency.
She added to Sveriges Television (SVT); "We have not yet got hold of them."
Police have so far declined to comment on the nature of the girl's injuries or elaborate further on the suspects. It's understood that the eight-year-old lived in the apartment where she was found in a grievous condition.
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The apartment complex has since been sealed off by police.