A cash trap was fitted to a Rushden High Street cash machine for 24-hours before it was noticed by engineers.
The device was fitted to the TSB bank ATM by thieves between Monday, January 7, at 7.30pm and the following day, Tuesday, January 8 at 7.30pm.
Cash traps are claw-like devices that are inserted into ATMs which then grab the cash before it can be retrieved by the customer.
The TSB cashpoint was found to be damaged on Tuesday evening.
Anyone with information or anyone who noticed someone tampering with the machine should call Northamptonshire Police on 101. Alternatively, they can contact Crimestoppers anonymously on 0800 555111.