text: Police remain hopeful they will find missing 11-year-old Luke Shambrook who went missing from a campsite in Victoria on Friday. An increased number of police and other emergency crews continue to scour the thick bushland areas around Lake Eildon in an effort to find the boy. Search co-ordinator Acting Senior Sergeant Andrew Walker said Luke had a “very high pain tolerance”, a factor that would work in his favour given he has now been missing for days. Scroll down for video . The Shambrook family with children (left to right) Luke, 11, Lauren, 7, and Matthew, 10 . Luke Shambrook was last seen on the national park at 9.30am on Good Friday. It is understood he wandered off and has not been seen since . “Hence the reason why we’re out searching. We’re still hopeful that we can find him,” Sgt Walker said. The 11-year-old, who is autistic, was reportedly seen walking near the Devils River on Sunday, four kilometres south of his campsite where he was last seen. Search crews have rushed to the location and police remain comfortable that the young boy is still alive. Luke has now been missing for four days. A Victorian Police spokeswoman told AAP late on Sunday that a family saw a young boy matching Lukes description while they were driving in the Devils River vicinity. With temperatures dropping to as low as eight degree Celsius, Senior Sergeant Ralph Willingham believes that the fourth day of searching will have a further level of urgency. 'The advice I'm getting from our search and rescue experts having regard to the overnight temperatures and the daytime temperatures is that he could well still be out there,' he said. 'We've got to be realists but we're positive, the family's positive.' However, Luke may not even know he is lost and is known to frequently hide, according to his family. He was last seen leaving Candlebark Campground in Fraser National Park near Lake Eildon at 9.30am on Good Friday. Luke has limited speech and his family says he is probably confused, and he may not even be aware he is lost. Campers are helping rescue teams including the air wing, dog squad, local police and SES volunteers in the search of thick bushland. Police hold hope that Luke has been able to stay reasonably warm as he was last seen wearing a beanie and warm jacket. There was a moment of hope when a beanie was found by the search party, however it was decided it did not belong to Luke. The Candlebark Campground in Fraser National Park, central Victoria, where Luke went missing on Friday . Having met Luke's family during a push to open a special school in Melbourne's southeast, Opposition emergency services spokeman Brad Battin says it's devastating to hear the 11-year-old is missing. He says Luke's parents Tim and Rachel have been updating him on the search and appreciate the efforts of all those out looking for their little boy. 'He's a lovely young kid,' Mr Battin told AAP on Sunday. 'He displays all the characteristics of a child with autism, which means he might not even think he is lost.' Sergeant Greg Paul says the search is focused on an area of several kilometres of bushland. 'We've got a lot of searchers in the bush, we've got a lot searchers searching all the tracks and in between the tracks and the gullies and the spurs,' he told reporters on Saturday. The Shambrook family has thanked emergency service workers, volunteers, family and friends for their help. They say the disappearance is completely out of character for him. A widespread search is being carried by search and rescue teams including the air wing, dog squad, local police and SES members, along with campers around the surrounding areas. A large search is being carried by a medley of search and rescue teams . Sergeant Greg Paul said the search was focused on an area of several kilometres of bushland. 'We've got a lot of searchers in the bush,' he told reporters on Saturday. 'We've also got people walking the banks of the lake.' But he outlined a serious hurdle for the search efforts, according to ABC. 'With the autistic condition, Luke might not respond to searchers, he may not even know that he's lost,' he said. 'He won't necessarily respond to his name being called, but that might change a little bit as he gets hungry maybe. Sgt Paul said there were hundreds of other campers in the area over the busy Easter period, so there was a chance someone else could spot Luke. Luke is described as being of medium build, about 150 cm tall with olive skin, brown hair and brown eyes. He was last seen wearing a black windcheater, black t-shirt, grey track-pants, grey boots and a scarf. Lake Eildon, near where Luke went missing: Police say conditions are favourable for his survival overnight, with warm temperatures through the day . Sergeant Greg Paul said the search was focused on an area of several kilometres of bushland . Searchers are desperately combing bushland and the banks of a lake for an autistic who went missing there . A widespread search is being carried by search and rescue teams including the dog squad and local police .
target: Luke Shambrook was last seen leaving Candlebark Campground on Friday .
  There has been an unconfirmed sighting of Luke with police acting quickly .
  The 11-year-old was reportedly seen walking 4 kms from his campsite .
  Police remain hopeful they will find Luke, who has 'high pain tolerance'
  Luke has limited speech and his family says he is probably confused .
  A large search is being carried by a medley of search and rescue teams .
  Police also said conditions are favourable for his survival overnight .
  They have issued an extensive description of Luke and his clothing .