Five-month-old baby triplets, Charlie and Noah were found not breathing when mum Sarah Owners, 29, went to check them on Saturday morning. Ethan, their third brother is said to be the only survivor.
Paramedics rushed the triplets to the Princess of Wales Hospital before Charlie and Noah were pronounced dead.
A South Wales Police representative said: 'The five-month-old children were conveyed to hospital where tragically they were later pronounced deceased.'
'There are no suspicious circumstances surrounding the deaths which are being treated as a tragic accident.'
It is yet to be confirmed what caused the tragic incident, but it is believed that the baby boys were poisoned with carbon monoxide due to a suspected malfunctioning heater.
Research is currently being conducted to determine the exact cause of death.
A GoFundMe page has also since been set up to help the family during this difficult time.
This article originally appeared on New Idea.