Detectives are looking for links between two raids on Credit Union offices in South Yorkshire.
On Monday three masked robbers armed with an electric stun gun escaped with thousands of pounds after bursting into Credit Union offices on Queensgate, Doncaster.
They threatened staff, who were forced to hand over cash.
Two members of the public and three children were there at the time.
Detectives are looking into the possibility that the robbery may be linked to a similar incident in Goldthorpe, where a Credit Union office was raided on Barnsley Road.
Call police on 101.