Staff opening up for the day on Thursday December 1 at Whitehall Garden Centre in Lacock were horrified when they were approached by a man carrying a gun.
Workers rushed to lock the doors and shut themselves in the garden centre after spotting the man, dressed in dark clothes and a balaclava, in Corsham Road at 7.15am on Monday (November 28).
The intruder fled and staff called police who sent an armed response team to search the area.
Michael Gingell, operations manager at Whitehall, said: ?The man was dressed in dark clothes, a similar colour to my work uniform, and a balaclava and he was carrying a gun, although we couldn’t tell if it was a handgun or a shotgun.
?It was at normal opening time, around 7.15am. It just came out of nowhere and was all over so quickly. There were only three members of staff here. We have footage on CCTV which we have given to the police. We have footage of him walking up and down in the car park before we had even opened.?
Once the door had been locked by the quick-thinking workers, the man fled the scene, heading towards the overflow car park.
?We think he came into the centre via the fields at the back and left the same way. He ran towards the footpath and went through to Folly Lane,? added Mr Gingell.
After the incident managers held a meeting to discuss what steps could be taken to ensure the safety of staff and customers.
?We had a meeting on Monday to look at upgrading the CCTV and security. We have highlighted a couple of key areas we will be improving. There is going to be a massive investment in security. You just don?t really expect these things to happen,? Mr Gingell said.
Wiltshire Police have described the man as being of medium to stocky build and wearing a dark coloured jacket, dark trousers and dark shoes or boots.
Detective Constable Tom Fenwick, of Trowbridge CID, said: ?This was, understandably, a very frightening incident for the members of staff involved, but fortunately, nobody was injured.
?Following the call, there was a heavy police presence in the area, including armed response officers, who carried out patrols and searches of the area.
?We are appealing for the public?s help with our investigation and would ask anyone who may have information or who may have seen any suspicious activity around Whitehall Garden Centre during the early hours of Monday morning to contact police on 101.?