Thames Valley Police has released three images of a knife used during a robbery in Thatcham.
The incident took place around 6pm on Wednesday (23/1) at Ladbrokes on Bath Road.
The offender entered the premises, carrying a knife and a black holdall bag, before going behind the counter and taking cash from one of the tills.
Members of staff locked themselves in a room during the incident.
After being tripped up by a member of the public when leaving the shop, the offender dropped the cash and knife, which were later recovered by police.
The offender ran away from the scene heading towards Green Lane and Lower Way.
There were no injuries.
The offender is described as a male, around 5ft 10ins tall and of average build. He was wearing dark clothing and a dark face covering.
Investigating officer, Detective Constable Pam Finch from Force CID in Newbury, said: “I am appealing for anyone with information about this incident to come forward.
“The knife recovered at the scene is very distinctive. If you recognise it, or have information that could help us to identify the owner, please contact Thames Valley Police.”
Anyone who has information about this incident can report the details on the Thames Valley Police website quoting reference 43190024120. Alternatively, you can call the non-emergency telephone number, 101, or contact Crimestoppers anonymously on 0800 555 111.