Police say they have not yet found a gun after an armed siege ground Brighton's Vogue Gyratory to a standstill for almost four hours yesterday.
This morning a police spokesman told The Argus: "No weapon has yet been found and enquiries continue to trace it.
"The 34-year old man arrested is still in custody for interview and further enquiries.
"The Firearms Act offence on suspicion of which he was arrested is the alleged possession of a firearm with intent to cause the fear of violence."
Sussex Police's armed response unit swooped at 2.17pm yesterday after reports a man had been seen with a gun.
At lest four officers armed with rifles and dressed in body armour, shields and helmets entered a block of flats at the Vogue Gyratory soon after.
Around 50 officers controlled a cordon around the scene for several hours and at about 5.30 a man wearing slippers was arrested inside and led out in handcuffs.
Police said no shots were fired and no one was hurt.