A man suffered a punctured lung after being stabbed in the back outside a Luton nightclub.
The attack took place at around 3.15am outside Exchange nightclub in King Street on Saturday, April 16.
It is believed the victim had clashed with someone outside the club and then approached door staff telling them he had been stabbed. He was taken to hospital after suffering a punctured lung.
DC Colin Knight said: “The victim received nasty injuries and we need to find whoever did this to him. It is believed he was stabbed by a white man, but we do not have any further description of his attacker at this time.
“We know the area outside the nightclub was extremely busy at the time and we urge anyone who may have seen something to contact me. Any information, no matter how small, could assist our enquiry, so please get in contact.”
Two men were arrested in connection with the incident, but were later released without charge.
Anyone with information contact DC Knight on 101.