A 49-year-old man is in a critical condition in hospital after being stabbed at a house in Lancaster.
Police found the man suffering from a stab wound to the chest when they were called to an address in Patterdale Road on Thursday evening.
The man was taken to Royal Lancaster Infirmary where he remains in a critical but stable condition.
A 20-year-old man has been arrested on suspicion of attempted murder and is being questioned by detectives.
The scene remains cordoned off while forensic examinations are carried out.