An East Cowes man was arrested on suspicion of having either a firearm or imitation firearm at the Co-op store on Friday evening (November 23).
Witnesses at the scene say the man was dealt with quickly by officers who sat him down behind the nearby cafe.
He was also arrested for possession of a Class B drug and remains in custody at this time.
A spokesman for Hampshire Constabulary said: “We were called to York Avenue shortly before 7.30pm.
“Officers arrested a 33-year-old man from East Cowes on suspicion of possession of a firearm/imitation firearm and possession of a Class B drug.
“He remains in custody at this time.”