Two robbers in balaclavas took hundreds of pounds from the till at a bookmakers in Halifax town centre.
The pair - one armed with a knife - burst into the store on Clare Road at 8.20pm on Tuesday and threatened staff and demanded cash.
They escaped with the money from the till and were headed towards Prescott Street.
One was described as Asian, 5ft 7ins tall, stocky, wearing a dark blue hooded top and carrying a knife.
The other was described as white, over 6ft tall, skinny and wearing a hooded jacket.
Detectives would like to speak to anyone who may have seen these men in the area at the time or who may be able to identify them.
Anyone with information is asked to contact Calderdale CID via 101 or CrimeStoppers anonymously on 0800 555111.