Two brothers were taken to hospital with head injuries following an assault otuside a Halifax nightclub.
Three men - aged 24, 25 and 25 - were arrested on suspicion of wounding with intent to cause Grievous Bodily Harm following the incident, which happened outside the Liquid nightclub at 4.15am on Sunday.
Police are appealing for witnesses after the serious assault, which happened just after the club was closing and customers were leaving.
It is thought that there was a disturbance involving a number of people and that immediately after that the two brothers - aged 20 and 21 - were assaulted by a group of men.
The brothers suffered facial injuries which required medical attention. Both have since been released from hospital.
Detective Sergeant Simon Archer, of Calderdale CID, said: “There were a lot of people around at this time in the morning and I am appealing to anyone who saw what happened to come forward.”
The three men who were arrested have been released on bail pending further enquiries.
Any witnesses are asked to call Calderdale CID on 101, or Crimestoppers, in confidence, on 0800 555111.