A nine-year-old boy killed in a holiday park dog attack was alone in a caravan with the animal, police have said.
Frankie Macritchie, from Plymouth, died at Tencreek Holiday Park, Looe, Cornwall, on Saturday.
Police said he was staying at the site with adults but they were in another caravan when he was attacked by a "bulldog-type dog".
A woman described by police as a family friend was later arrested at a railway station near Plymouth.
The 28-year-old, held on suspicion of manslaughter, has since been released.
Det Supt Mike West said Frankie had been on holiday for a number of evenings before his death.
"We believe that Frankie was alone in a caravan with the dog as he was attacked, whilst the adults that he was on holiday with were in an adjacent unit," he said.
"These two groups of people were all known to each other and all from the Plymouth area."
Police were called to the holiday park at 05:00 BST on Saturday and found Frankie "unresponsive".
Mr West said Frankie was found by members of the public.
"There was sounds of a disturbance and sounds of distress coming from that caravan and immediately on hearing that members of the public ran towards it and attempted to render first aid to Frankie," he said.
Frankie died at the scene and a search was launched to track down the dog and its owner.
The 28-year-old woman arrested on suspicion of manslaughter was also arrested on suspicion of having a dog dangerously out of control.
The dog was transferred to kennels, where it remains.
Mr West said whether or not the dog was put down was not a decision for police and inquiries were ongoing about the exact breed of the dog.
Mr West said it was a "desperately sad event".
"I also wish to recognise those who came to his aid at the scene," he said.
"We appreciate that this case will shock and upset the public, however, we urge the public not to apportion blame on this tragic incident."
Police urged people not to speculate about what had happened on social media.