(CNN) -- Police have found evidence that "strongly indicates" a 12-year-old boy who was witnessed being snatched by a crocodile in a remote part of Australia was killed in the attack. 
 
 "No specifics will be given in relation to the trauma or type of evidence located out of respect for the family," acting police commander Michael White said in a statement Tuesday. 
 
 The family of the boy -- who would have returned to school Tuesday after the summer break -- have been informed, a spokeswoman for the Northern Territory police, Rebecca Forrest, told CNN. 
 
 "As expected they're grieving," Forrest said. "But the evidence is there that he's deceased." 
 
 As search crews continued to gather evidence Tuesday, shoot-to-kill orders remained in place for crocodiles longer than two meters around the small community where the attack occurred. 
 
 Three animals have been killed so far, ranging from 2.5 to 4.7 meters in length, Forrest said. 
 
 The boy had been swimming with four other children in a water hole near Mudginberri in the Northern Territory's Kakadu National Park on Sunday afternoon, when a saltwater crocodile attacked the group. 
 
 One of the boys, aged 15, was bitten by the animal but managed to escape. The crocodile then turned on his friend, aged 12, said police sergeant Stephen Constable. 
 
 "The 15-year-old boy was grabbed on his right arm. He started fighting off the croc, and it took him by the left arm; then it let him go and took hold of the 12-year-old boy, and swam off with him." 
 
 Police officers and park rangers have been using helicopters and boats to search the area since the attack occurred. 
 
 A crocodile expert who examined the first boy's wounds, believed the crocodile was between 2.5 to three meters long (around eight to nine feet), Constable said. 
 
 Search crews have also been looking for larger crocodiles that may have attacked the one that took the 12-year-old. 
 
 "On occasion a smaller crocodile may take some food, and a bigger crocodile will take it off them," said Constable. 
 
 According to local media reports, people had been warned against swimming in the area after a teenager survived an attack by a five-meter-long crocodile in the region in January last year. 
 
 Constable said this time of year is particularly dangerous due to seasonal flooding. 
 
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 CNN's Pierre Meilhan contributed to this report. ||||| A 12-year-old boy is feared to have been killed in a crocodile attack – the 14th in the past 12 years – leading to calls for a cull on a booming population of the saltwater reptile in Australia’s Northern Territory. 
 
 It is believed the boy was taken by a crocodile measuring up to 3m long while swimming with four friends in a remote billabong in the world-heritage listed Kakadu National Park on Sunday. 
 
 Before the boy was taken, the crocodile attacked one of his teenage friends, who fought off the reptile, suffering bites to his arm. The 12-year-old boy disappeared shortly later. Members of the group who had been swimming in the Mudginberri Billabong, about 170 miles east of Darwin, said they believed the crocodile had turned on and taken the missing boy. 
 
 A large-scale land, boat and air search for the boy’s body in and around Magela Creek, which feeds the waterhole, is under way, but has been hampered by poor conditions caused by the rainy season. Officers, with orders to shoot to kill any crocodile longer than 3m, have so far come across and shot two crocodiles measuring more than 4m. 
 
 If confirmed, the boy’s death will be the sixth time a child has been killed by a “saltie” in the past 12 years. 
 
 The attack has led to calls from indigenous elders for a cull of the reptiles, whose numbers have been growing unchecked in the region over the past three decades. Crocodiles are so numerous in the Northern Territory today that they have even been found stalking the waterways of suburban Darwin and snatching dogs. 
 
 Justin O’Brien, chief executive officer of the Gundjeihmi Aboriginal Corporation that represents the Mirarr Traditional Owners of the area, said the threat from crocodiles in Kakadu National Park, one of the Northern Territory’s most popular tourist destinations, must be urgently addressed. 
 
 "People have been swimming in these waterways for tens of thousands of years. Adults in the community have memories of swimming happily in these waterways,” he told the Northern Territory News. 
 
 "For the past 30 years many Traditional Owners have been saying there are too many crocs and that the numbers need to be managed.” 
 
 Mr O’Brien said traditional owners wanted a review of the management of crocodiles in their communities “in response to their increasing numbers and safety concerns”. 
 
 Last year a teenager fought off a 5m crocodile in the same area, and the region is well signposted as a crocodile danger zone, but lack of recent sightings could have lulled the group of boys into believing the billabong was safe. 
 
 The wet season in Kakadu is the most dangerous time of year to be swimming in waterholes and creeks. 
 
 Saltwater crocodiles can grow up to seven metres long and weigh more than a ton. But the smaller reptiles can be just as dangerous, especially to children. 
 
 Their numbers have increased steadily since the introduction of laws protecting saltwater crocodiles in 1971. It is now estimated that some 75,000-100,000 roam the northern reaches of the country. 
 
 The most recent fatality was in August last year, when a man was taken by a 4.7-m crocodile as he swam across the Mary River, 68 miles east of Darwin.
– A teen swimming with a group of friends in Australia's Kakadu National Park yesterday was attacked by a crocodile and escaped—only to have the croc move on to one of his friends, a 12-year-old now believed dead. The Telegraph reports that if the younger boy was indeed taken by the saltwater crocodile, it would mark the sixth time a "saltie" has killed a child in the last 12 years, and that's led to renewed calls for a cull. Laws protecting the salties were put in place in 1971, and their ranks have swelled since, with as many as 100,000 of them occupying the Northern Territory. Sky News reports officials are going to great lengths in an effort to recover the boy's body: A trap has been set in Magela Creek, which feeds the waterhole; air, land, and boat searches have taken place; and any croc measuring more than 6.5 feet can be shot. And so far, two have, though slicing them open revealed no human remains. And the search efforts have been hampered by seasonal flooding, while has swelled the creek from a width of about 650 feet to more than 3,000 feet. The 15-year-old who was attacked was grabbed on his right arm and then his left, reports CNN. Based on the bite marks, the crocodile is believed to measure eight to nine feet. (A 26-year-old was killed by a croc in the area last year; more on that here.) Meanwhile, Australia has already launched another cull: of sharks.