A baby girl's body was found buried beneath the sand of an Australian beach on Sunday, authorities told the BBC.

Two boys, ages six and seven, were digging in the sand on Sydney's Maroubra beach when they came across the baby buried 12 inches below, police said. An autopsy was needed to determine the baby's sex because the body was too decomposed.

Authorities confirmed on Monday the baby was a girl, CNN reported. No other details, including the manner of death, have been revealed.

"Obviously everyone is upset," Police Inspector Andrew Holland told the BBC. "It's a tragic event. Something like this doesn't happen every day and it affects everyone involved."

Investigators are also searching for birth records and are contacting local hospitals to determine the identity of the baby and her parents.

Holland added that police are concerned for the welfare of the mother and urged her to come forward.

"Come and talk to us, seek some advice, we need to talk with you," Andrew Scipione, commissioner of the New South Wales state police, told the BBC.  

Police said the boys who found the baby, who was buried without clothes, are receiving counseling.

The incident comes a week after another baby almost died from being abandoned in a storm-water drain in western Sydney. Nearby cyclists found and rescued the baby boy on Nov. 23, five days after he was left in the drain, police told CNN.

Police arrested the boy's 30-year-old mother and charged her with attempted murder for allegedly pushing the child through the drain. She is expected to appear in court on Dec. 12.