Firearms officers responded to a report of gunshots being heard in First Avenue, Hove, on Sunday night (19 September) at about 9.30pm.
The road was closed off and the NPAS police helicopter was called to help with the search.
A man was arrested for possession of a firearm in a public place and possession of a firearm with intent to cause fear and alarm. He is currently in custody. No one has was harmed.
Chief Superintendent Justin Burtenshaw said: “This is a fast moving investigation and I want to reassure the public that there is no threat to the wider community. This is not terrorist-related. We will continue to have a number of officers in the area while we continue our enquiries and I would like to thank the community for their patience and understanding.”