Masked men armed with a gun and a knife robbed a bookmakers in Oxfordshire.
Two men threatened a cashier at Betfred in London Road, Headington, on Tuesday at 2000 GMT, and ordered him to put money into a bin bag.
Thames Valley Police said the men escaped with a "small sum" of money. No one was injured.
Detectives said two men, both aged 25, and a 22-year-old woman have been arrested in Oxford in connection with the robbery and are in custody.
An imitation firearm and a knife have also been seized, officers said.