A 10-year-old boy died when he was attacked by a “bulldog-type” dog at a holiday park, police said.
Police were called to a caravan at Tencreek Holiday Park in Looe, Cornwall, just before 05:00 BST to reports the boy was “unresponsive” after the attack.
He died at the scene and a search was started to find the dog and owner.
A 28-year-old woman was arrested at 08:00 in Saltash on suspicion of manslaughter.
Devon and Cornwall Police said she was also arrested on suspicion of having a dog dangerously out of control.
They said the boy’s next of kin were aware and were being supported by police officers.
Officers said the dog had been found and had been transferred to kennels.
‘Police already there’
South Western Ambulance Service said paramedics were sent to the park at 04:42.
Tencreek Holiday Park hosts touring, camping and seasonal pitches as well as static caravans.
Its website says facilities on site include children’s entertainment, an indoor swimming pool and a sports pitch.
In a statement, holiday park manager Robert Ellwood said police had not given him any information about what had happened.
“I arrived this morning and police were already on site,” he said.
“Due to the amount of police we knew it would be something major but we have not been told anything.”
The mayor of Looe, councillor Armand Toms said the “tragedy was so sad for the family” and his thoughts were with them.
He said: “This community will do whatever it can to help.
“It always has done and will in the future and I am speaking not as the town’s mayor but as someone born and bred here.”
Mr Toms said the holiday park had been “part of our community” for about 40 years.