Four children and their father have been found dead in a gas-filled car at a beauty spot in north Wales.
All four of the Young boys died
The car was discovered at the Horseshoe Pass near Llangollen in Denbighshire at 0130 GMT on Thursday.
Police have named the victims as seven-year-old Joshua Young, six-year-old Thomas Young, five-year-old Callum Young, three-year-old Daniel Young, and Keith Young, 38.
The results of the post mortem examination has revealed they all died of carbon monoxide poisoining.
The family came from Winsford in Cheshire.
The gas-filled car was discovered two hours after the children's mother, Samantha Young, rang police in Cheshire saying she was frightened for her children's safety.
She had received a phone call from her husband saying he would harm the children.
Police managed to trace his mobile to Llangollen and a North Wales Police dog handler located the car.
The frame of mind to do that sort of thing to four young people beggars belief
Joe Clemence, restaurant owner
A petrol lawnmower was found running at the back of the car.
Although the couple were separated, the dead man had legal access to the children.
It is understood he took the children to Horseshoe Pass during an arranged access visit on Wednesday.
The children's bodies were taken to Wrexham Maelor hospital where they were confirmed dead.
Mrs Young is being comforted by relatives, and a police liasion officer is with her.
A neighbour in Cheshire, Irene Perry, said she "just cannot believe it has happened".
"He must have gone over the top because he loved them," she added.
North Wales and Cheshire police forces are launching a joint investigation, but officers are not looking for anyone else in connection with the deaths at present.
DI Gwyn Jones from North Wales Police said it was one of the most shocking scenes he had come across in 22 years serving with the force.
Other officers had been "deeply traumatised" by the sight, he added.
Deputy Chief Constable Bill Brereton, said the incident was "horrendous beyond my imagination".
"With the death of a child, and here we have four babies really, it is horrendous beyond my imagination," he added.
The bodies were found at Horseshoe Pass, near Llangollen
He added the officer who found the children would be offered counselling.
Joe Clemence, who owns the Ponderosa Cafe on the Horseshoe Pass, said he was "flabbergasted" at the tragedy.
"We are absolutely flabbergasted - the frame of mind to do that sort of thing to four young people beggars belief," he told BBC Wales.
Although situated two miles from the nearest village, Mr Clemence said the deaths would have an impact on communities as far away as Llangollen.
"Particularly, when children are involved," he added.