A 25-year-old man has been arrested after a newsagent was robbed in Portslade.
The robbery happened just after 6.15am on Monday (5 January), Sussex Police said.
A man went into Martins, in Valley Road, Portslade, threatened a man working there with a knife and took £2,900 from the safe in a back room.
No one else was in the shop at the time and the staff member was not hurt.
A man from Portslade has been arrested on suspicion of robbery and has been bailed until Wednesday 18 February while investigations continue.
Police do not believe that there is any connection with the Martins robbery and four similar robberies in the area in November and December.
Two 17-year-old boys from Hove have been arrested on suspicion of robbery in connection with the other four robberies.
They have been bailed until Friday 23 January and Sunday 25 January while inquiries continue.
