An armed robber threatened staff at a Hove travel agency, tied them up and fled with a substantial sum of cash.
Sussex Police said that he waved what was thought to be a handgun at staff during the robbery on just before 5pm on Friday (28 December).
He assaulted one women member of staff at the Thomas Cook branch in Church Road, Hove, although Sussex Police said that no one was injured during the robbery.
The robber stole cash in various currencies, travel cards and travellers cheques.
The man was described as about 5ft 8in tall. He was wearing a black Puffa-style jacket with a grey hooded top underneath and a balaclava.
DS Mark Rosser said: “This was clearly a very distressing incident for those who found themselves confronted by this man.
“We are offering them support and are making every effort to identify, locate and arrest him.”
He urged anyone who saw the robbery, had any information or was offered foreign currency to call Sussex Police on 101 or the independent charity Crimestoppers anonymously on 0800 555111.