A man sustained serious head and facial injuries and another a broken leg during a pub row.
The incident occurred in a pubic house on Park Avenue in the Rosemount area of Derry shorty before 7.00pm on Tuesday last.
A 23-year-old man sustained a suspected fractured skull and broken jawbone and was taken to Altnagelvin Hospital.
A 44-year-old man was subsequently arrested on suspicion of causing grievous bodily harm with intent.
He was also admitted to hospital with a suspected broken leg.
Two men are alleged to have been involved in the initial incident.
One ran off along Lower Nassau Street after the incident while the other got into a car that was outside the bar.
A PSNI spokesperson asked anyone who saw what happened is asked to contact police at Strand Road on the non-emergency 101 telephone number.
Alternatively, information can be given anonymously to the Crimestoppers charity on 0800 555 111.