A Thomson shop is Ruislip was robbed on Tuesday April 13 while three members of staff were in the store.
The staff were threatened with a weapon and money was stolen from the foreign exchange bureau but nobody was injured.
A passer by contacted the police as the intruders, who were reportedly wearing balaclavas, entered the store. As a result, police caught the intruders as they left the premises and recovered all the money.
A Thomson spokesman said: “Customer and staff safety is of the utmost importance to Thomson.
“All retail staff follow a strict training programme which includes advising them how to act should an isolated incident of this type occur.
“The company is also offering those members of staff, affected by this incident, support and assistance at this time in association with a recognised counselling body.
“While the police investigation is ongoing, we are unable to comment further on the specifics of this case. However, we are fully complying with the authorities and hope that the investigation comes to a swift and satisfactory conclusion.”