A man was arrested from his car in Keighley following an incident in which a woman was allegedly attacked.
The 43-year-old woman was discovered with severe facial injuries in her third-floor flat at Gerard House, Fairhaven Green, Thorpe Edge, on Sunday evening.
A 52-year-old man was later arrested in Keighley on suspicion of causing grievous bodily harm.
He was this week detained in Airedale Hospital, where his condition was described as stable, and officers were waiting to interview him.
Detectives were also waiting at the bedside, in intensive care at Leeds General Infirmary, of the woman.
Her condition was described as critical but stable, and she was under medical sedation.
Police were alerted to the incident just before 7pm on Sunday, and they forced entry to the flat.
Forensic experts were examining the flat this week and house-to-house inquiries were taking place in the area.
Detective Chief Inspector Steve Snow, of West Yorkshire Police, who is leading the investigation, said: “There was a serious assault in the flat. We don’t know if any weapons have been used, but the victim has sustained severe facial injuries.”
He added that inquiries were taking place in a bid to trace any potential witnesses and it was hoped that forensic examinations would help to determine what had happened inside the property.
Residents said they had heard police forcing their way in and one neighbour said she had heard a woman, believed to be the victim, shouting earlier in the evening “on the verge of screaming”.
Marjorie Clapham, 80, who lives directly above, went to peer over the balcony after hearing loud bangs.
“Some kids had been kicking a ball against the wall earlier and I thought it was just them, but then the bangs got really loud. When it got really noisy, I went outside and saw the police – I knew it had to be something bad.”