A murder inquiry has begun after a man who was stabbed in the chest died.
The victim was found unconscious by emergency services at a property in Acregate, Skelmersdale, at about 04:40 GMT.
He was taken to hospital, but was declared dead shortly afterwards.
A 36-year-old man, from Skelmersdale, is being held in police custody on suspicion of murder. A post-mortem examination is due to take place later, Lancashire Police said.
The force has issued an appeal for anyone with information to contact them.