Two white van men could hold the key to a double shooting at a Berkshire tattoo parlour, detectives believe.
Armed police were called to Fantasy Fine Line in St Mark's Road, Maidenhead, at 1230 BST on Monday.
Detectives believe the men inside the van which pulled up as the shooting happened could be "vital" witnesses and stressed they were not suspects.
Two men, aged 45 and 51, were taken to hospital with leg and shoulder wounds. A 47-year-old man has been arrested.
Police believe up to four men were involved in the shooting.
Officers are attempting to trace the two men in the white transit-style van which pulled up opposite the parlour at the same time as the shooting.
One of the men got out and removed a road sign.
Det Supt Rob Mason said: "I would like to stress that I do not believe these people are involved in the incident but may have vital information that could help us with our inquiries."
Police said the shooting was an isolated incident and there was no risk to the public.
One of the injured men has been discharged from hospital while the other is still receiving treatment.
The 47-year-old man arrested at the scene continues to be questioned by police.