Police believe the victims were murdered by a killer who torched their home in a bid to cover up the crime. Firefighters discovered the bodies early on Sunday morning when they were called to a house at Clydach, Swansea.

Post mortems have been carried out on Doris Dawson, 80, her daughter Amanda Power, 34, and grand-daughters Katie, 10 and Emily, eight.

Detective Superintendent Martyn Lloyd-Evans, who is leading the case, said: "It is my belief that these people have been attacked first and the fire is merely a way to try to conceal what has taken place.

Plastic sheeting shields the front of the family home

"All four victims have suffered injuries. Whoever has done this would be bloodstained and after the crime they have gone home somewhere.

'There must be a motive'

"There must be a motive for this dreadful incident. It is important that we get to the bottom of this as soon as possible."

Forensic scientists conducted a fingertip search around the family's semi-detached home on Sunday. The front of the house was screened off with plastic sheeting.

Victims unconscious

Mr Lloyd-Evans said Mrs Power and her two children were last seen at about 0030BST on Sunday when they returned to the house, which was owned by Mrs Dawson, after babysitting for a friend.

All four victims were unconscious as they were pulled out of the blazing home and attempts to revive them at the roadside were unsuccessful.

Police say a number of fires were started in the house in Kelvin Road, Clydach, near Swansea, after the two women and the girls were assaulted.

Shouts in the dark

One neighbour said she heard shouts coming from the house shortly before the emergency services arrived at 0430BST.

Teachers at Katie and Emily's school, Craig Cefn Parc Primary School, will be doing their best to comfort their friends on Monday.

Head teacher Jean Healey is due to address the youngsters at a special assembly service on Monday.

She said: "They are going to be coping with their grief because the two little girls were very well known and had lots of friend here. They will be very sorely missed."

Mrs Healey said: "I don't know what I will say to the children at the assembly because it will very much depend on how they react this morning."