A 19-year-old man is in critical condition in hospital with burns suffered when he tried to help a woman targeted in a petrol bombing in west Belfast.
The PSNI believes the attack on three people in a house in the Ballymurphy area, is associated with an ongoing feud involving two well-known local families.
The firebombing victims were in the house in New Barnsley Crescent at about 10pm on Wednesday when the window was broken by a block and some petrol and a firebomb were thrown inside.
The young man was badly injured when his clothes caught fire as he tried to help Elizabeth Burns put out the flames.
Two men were seen running from the area afterwards and officers are investigating reports some clothing may have been on fire. They have asked if anyone has sought treatment for burns on either side of the Border since Wednesday night.
Chief Supt David Boultwood said: "The feud is the main line of inquiry. This was an absolutely horrendous attack and it really beggars belief why people would carry out such an attack. We are treating it as attempted murder because whoever carried this attack out clearly intended that people would die as a result." He appealed for the public to come forward with information.