(CNN) A baby was spotted by a passerby crawling near a road in Fiji's Nausori Highlands close to where five family members were found dead, according to a police statement.

The discovery of five bodies, three adults and two children, was made on Monday after the one-year-old baby was found nearby.

A postmortem examination discovered that the five victims had ingested an "alleged substance ... which resulted in their deaths," according to a post on Fiji Police's verified Facebook account.

Police added that more tests will be conducted by the Fiji police chemistry lab in Nasova.

The child has been taken for medical treatment at Lautoka Hospital, police said, as investigators gather information at the scene to establish the identity of the victims.

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