Masked raiders threatened staff at a village post office with knives before emptying the safe and stealing the till.
The three men, whose faces were covered with balaclavas, burst into Hathern Post Office and convenience store, near Loughborough, and escaped with about £15,000.
Staff and a customer were threatened with a 10-inch knife and told to open the till and safe.
The raiders even stole bags from a female member of staff and a customer who was present during the raid.
The incident took place shortly after 5pm on Thursday, October 11.
A member of staff at the Cross Street shop, who was on the phone to her husband when the raiders entered, said: "I haven't got over it yet, I'm still shaking."
The robbers told the woman to open the till and knocked the phone out of her hand.
She said: "It felt like they were in here for ages but it was all over pretty quickly.
"I was panicking and shaking and I couldn't open the till because it's a new one and works differently to the one we had before.
"One of them tried to open it but couldn't do it, so he picked it up and pulled it along the counter until all the wires came out. They took the till and forced us to open the safe and they emptied that.
"It was so slick and well-thought out I'd be amazed if they hadn't done it before.
"We've been burgled before, but we've never experienced anything like this – it was terrifying."
The woman's husband dashed to the scene but did not get there until after the gang had escaped.
Police have appealed for help tracing the men, who are thought to have left the scene in a grey silver Vauxhall Astra.
Anyone with information should call Detective Constable James Willoughby of Leicestershire Police on 101, or Crimestoppers, which is anonymous, on 0800 555 111.
