Gwent Police is appealing for information and witnesses following a robbery on Thursday February 3, in New Tredegar.
At 9.50am, raiders entered the Post Office on Elliot Street and sprayed a female member of staff in the face with a fire extinguisher.
The two men then went behind the counter and stole a significant amount of cash.
They made off in a silver Ford Fiesta in the direction of Aberbargoed.
The woman working in the Post Office was not seriously injured but was left shaken and taken to Prince Charles Hospital as a precaution.
Two local men, aged 23 and 26, have been arrested on suspicion of robbery and are currently in police custody.
Police are appealing for anyone who may have information about the incident to contact them. They are particularly interested in tracing the silver Ford Fiesta which is identifiable by the black, purple and red dot stickers all over its boot.
Anyone with information should call 01633 838111 or Crimestoppers anonymously on 0800 555111.