(WXIN) — A homicide investigation is underway in New Zealand after a family found the remains of two children inside suitcases they bought from a storage facility in an online auction.

The family alerted police to the discovery last week after finding the remains inside the suitcases. New Zealand police characterized the find as “extremely upsetting.”

The family who bought the suitcases doesn’t have anything to do with the remains, police said, and is cooperating with the investigation. Police have asked the media to “respect their privacy at this difficult time.”

Police said the family was “understandably distressed” by the discovery, which was made in the South Auckland suburb of Manurewa.

An examination of the remains found that the suitcases contained the remains of two elementary school-aged children, police revealed Wednesday.

“Early indications suggest these children may have been deceased for a number of years before being found last week,” said Detective Inspector Tofilau Faamanuia Vaaelua.

“Formal identification procedures are still ongoing, which means police are not yet able to comment on the identities of the children,” he said.

Police are investigating the circumstances surrounding the deaths of the children and how their remains ended up at the storage facility.

“We are continuing to treat this matter very seriously and we are determined to hold the person, or persons, responsible for the deaths of these children to account,” Vaaelua said.