NORTHERN TERRITORY, Australia (CNN) -- Evidence indicates that a crocodile killed a young swimmer Sunday in northern Australia, police said.
Testing will determine whether DNA belongs to the 11-year-old who was swimming in the Black Jungle Swamp. She was with three other children -- two girls ages 7 and 10, and a boy, 12, authorities said.
The children reported seeing a crocodile tail and mouth in the water near where the girl was swimming, according to police.
Searchers worked late into the night in shoulder-deep water to find the girl, said Territory Duty Superintendent Michael Murphy. He declined to specify the type of evidence found.
"Everyone involved in this event has been working under difficult conditions. This is a heartbreaking event for the family and the community," Murphy said.
He urged the public to be cautious when swimming in the area during the wet season because tidal changes can cause crocodile movement.