A 16-year-old boy has been arrested after the body of a 13-year-old girl, who went missing on the weekend, was found in bushland in regional Victoria.

Victoria police said they were treating Layla Jeffery’s death as “suspicious” after her remains were found in Donald, a small town in western Victoria, late on Thursday afternoon following an extensive search.

On Friday evening, police announced they had arrested the 16-year-old boy from the Swan Hill area after a warrant was executed in Donald. Swan Hill is about 90 minutes drive away.

The boy was being interviewed by police on Friday night.

Speaking to media, Det Insp Dave Dunstan, from the Victoria police missing persons squad, said it was believed the boy was known to both police and the victim. Authorities ruled out any involvement by Layla’s family.

“We are quietly confident those responsible are now in custody. We don’t believe anyone else was involved in this situation,” Dunstan said.

Two women, a 53-year-old from Donald and 55-year-old from Melbourne, were also assisting police with inquiries. They have not been arrested.

A large-scale search had been conducted in bushland west of Byrne Street in Donald after Layla was reported missing on 5 July. She was last seen on McCracken Street the previous day.

Local police, along with specialist officers from the dog squad, air wing and search and rescue squad, were involved in the search.

“The remains are yet to be formally identified, but they are believed to be those of missing 13-year-old girl, Layla,” police said in a statement on Friday.

A warrant was executed at a residential property in Donald shortly after 11am on Friday as part of the investigation.

“The investigation into the circumstances around the death of the girl remains ongoing; however, police are currently treating it as suspicious,” the police spokesperson said.

Residents in the small town of about 1,500 people came together following the devastating news.

“We have been in contact with Layla’s family and our thoughts are with them at this heartbreaking time,” Dunstan said. “It is a tragic outcome for the Donald community and we urge people to seek support if they are affected.”

Buloke shire councillor, Charmaine Delaney, who “knew Layla and her family personally”, said “this tragic news has been unimaginable”.

“Layla was a giant, gentle, quiet little girl who just loved life … and to imagine that somebody would take her life away in a small regional town like ours is really hard to cope for the community,” Delaney said.