A man has been stabbed to death and his partner is fighting for her life after an incident at a Lancashire caravan park, police said.
A murder inquiry has been launched after the events early on Sunday morning in Heysham.
A police spokesman said that at 12.45am officers were called by the ambulance service to reports that a 26-year-old woman had been stabbed at Stud Farm Holiday Park.
Upon arrival officers discovered the woman suffering from serious stab wounds to the neck, stomach and back. Her 28-year-old partner was found nearby also suffering from stab wounds.
Both were taken to the Royal Preston Hospital, where the man died of his injuries. The woman has since been transferred to Royal Blackburn Hospital where she remains in a critical condition.
The spokesman said: "Following extensive inquiries a 26-year-old man was arrested by officers in Stoke on Trent and will now be questioned by Lancashire detectives on suspicion of murder and attempted murder."
It is believed the man arrested is known to both victims.
Detective Superintendent Paul Withers from the Force Major Investigation Team said: "This is a rare and appalling incident whereby a young man has lost his life and a young woman remains in hospital fighting for her life.
"An investigation is under way into the circumstances of exactly what has happened but I'd appeal to anybody that is staying at the caravan park or lives in the immediate vicinity that heard any commotion or witnessed any part of the incident to contact police.
"Officers working on the inquiry are searching for the knife that they believe was used in the attack but this remains outstanding at this time."
Anyone with any information was urged to contact Lancashire Police on 101 or CrimeStoppers anonymously on 0800 555 111.