A man is has been detained and questioned after police search.
Police were called at 4.40pm on Monday (April 19) to report of a man seen to be in possession of a suspected firearm, in an alleyway that runs between the Sainsbury's store and Causeway, in Horsham.
Officers carried out an extensive area search and the suspect was safely detained.
He has been taken into custody for questioning.
This incident is being treated as isolated and there is not thought to be any threat to the local community.