Raiders escaped with cash and travellers' cheques after demanding money from a travel agency yesterday.
The two men were handed a "substantial" amount at Going Places in The Boulevard, Crawley, after walking into the office just after 4pm.
They did not appear to be carrying weapons and did not threaten the staff.
Both were black, about 25 to 30 and about 5ft 10in tall.
One wore a black waist-length jacket, a blue Nike cap, grey trousers and grey trainers.
The other wore a hat which with ear flaps, had a moustache and goatee beard and wore a brown waist-length jacket.
Police at Crawley want to talk to anyone in the area between 3.50pm and 4.20pm yesterday.
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