Theresa May has praised the "bravery and professionalism" of the emergency services who were called to deal with a fire in rural Powys that is believed to have claimed the lives of a father and five young children.
A father and five children, aged between four and 11, are believed to have died in the blaze that ripped through a farmhouse in Llangammarch Wells.
Three children, aged 13, 12, and 10, managed to escape the fire and remain in hospital with non-life threatening injuries.
Brecon and Radnorshire MP Chris Davies brought up the incident during Prime Minister's Questions.
Mrs May described the fire, which broke out at a farmhouse in Llangammarch Wells, Powys, in the early hours of Monday morning, as a "tragic case".
This was indeed a terrible tragedy that took place and as he said it isn't just the family themselves that have been affected by it but the local community,.
Mrs May said she was sure everyone across the House would wish to send condolences to the family and friends of those affected.
Mrs May said Secretary of State for Wales Alun Cairns had spoken to the police and would remain in touch over the coming days.
She added: "Our emergency services do do an amazing job protecting us, we see this in so many instances, they never know when they are going to be called out to such a tragic incident."
Locals said Mr Cuthbertson, who lived in the area for decades, had around 17 children.
The cause of the fire is unexplained and specialist scientists and fire investigators remain at the scene.
Dyfed-Powys Police said it could take weeks to identify those killed in the fire because of the extent of the damage.