A 79-year-old man was taken to hospital following an alleged assault.
Police were called to High Street, Blackwood, Caerphilly county, on Thursday at about 15:00 GMT.
The injured man is said to be in a stable condition in hospital. Details of his injuries are not known.
Gwent Police said a 35-year-old man from Cardiff had been arrested on suspicion of assault.
He has since been released on conditional bail pending further inquiries.
The force is appealing for witnesses, external.