A man and woman are in hospital after being found with multiple injuries, police said.
A woman in her 60s and a man in his 70s were found in the house in Shalbourne near Marlborough in Wiltshire by paramedics at about 19.30 BST on Monday.
A man in his 40s from Hampshire has been arrested on suspicion of attempted murder.
Det Insp Mark Kent of Wiltshire Police said he "is known to the two victims".
The woman has serious head injuries and is in a critical but stable condition and the man is in a serious but stable condition.
The arrested man is being questioned at Gable Cross police station in Swindon.
Det Insp Kent said there would be a "heightened police presence" in the area as inquiries continue and sought to reassure people that "there is no risk to the wider public in relation to this incident".