Police said petrol had been used to start the blaze at the home of Michelle, 30, and Leslie Beattie, 36, at Cramlington, Northumberland.
A worried friend had made an emergency call to police as the two argued. The man was looking after their five-year-old daughter Gemma and two policemen were talking to him when they heard a scream. The officers forced their way into the bedroom and found the couple alight. They managed to get them out of the room and douse the flames.
Last night Mrs Beattie was said to be 'critical' with 41 per cent burns and her husband 'poorly but stable' with 30 per cent burns in Newcastle General Hospital. The second floor of the house was gutted in the blaze.
'We were called to a domestic dispute and let into the home by the family friend who had made the emergency call,' a Northumbria Police spokesman said.
'The couple were upstairs in a bedroom and when our officers heard a scream they burst into the room and found the couple alight.'
Neighbours had to be evacuated as fire-fighters fought to stop the blaze from spreading.
Police said they were not seeking anybody else in connection with the incident.
Mr Beattie was among an as yet unspecified number of Nissan car plant workers who this month volunteered for redundancy in return for six months' pay.