Police were called to the McColls post office and shop at Ongar Road at about 5.45am today, Thursday July 28.
Two suspects are believed to have waited until staff arrived then forced the manager to open the safe. The manager was later treated by paramedics after suffering face injuries and taken to hospital for further assessments.
A five figure sum of cash was taken by the two men who fled from the back door and into Doddinghurst Road where it is thought they had a vehicle waiting.
DI Rob Staples who is leading the investigation said: “This was a vicious robbery in which two suspects waited for staff to arrive then assaulted the manager while forcing him to open the safe.
“We want to hear from anyone who might have seen these two men hanging about in the area before staff arrived or may have seen them running away towards the Robin Hood pub then into Doddinghurst Road. We have no details about the getaway vehicle at this stage.”
One of the suspects was black and was wearing a blue showerproof coat. The second man was white.
Anyone with information should contact detectives at Loughton on 101 or call Crimestoppers anonymously on 0800 555111.