Hopes are fading that a nine-year-old boy snatched by a crocodile at a remote Northern Territory swimming spot will be found alive.
The child was swimming with a group of people at Port Bradshaw when he was grabbed by the crocodile at about 12.30pm (local time) on Saturday, Northern Territory police said.
Adults threw spears at the animal but it responded by dragging the boy into deeper water.
A massive search is under way and four members of the NT water police flew east from Darwin on Sunday, a police spokesman told AAP.
They join officers from Nhulunbuy Police station, based about 80km north of the attack site, as well as local sea rangers.
A police spokesman said the search would likely continue throughout Sunday afternoon but grave fears were held for the boy.
"Not too many people come away from a crocodile attack, I'm afraid," he said.
News Limited reports the four-metre beast was spotted on Sunday and fired on twice.
Superintendent Michael White earlier said the attack offered a grisly warning to all Territorians.
"This is a tragic circumstance for the child's family and friends and highlights the dangers of swimming in waterways in the top end," Supt White said in a statement.
The attack on the nine-year-old boy comes a fortnight after a seven-year-old girl was taken by a crocodile while she was swimming with other children and an adult at a local waterhole in the NT.
The girl was at the Gumarrirnbang outstation, 100km west of the remote community of Maningrida, when she was grabbed on November 17.
A three-metre crocodile was shot dead in the billabong the next day and the girl's remains were found inside.