Mr Darvinder Kang was locking up the Hyperama cash and carry business in Richmond Street, West Bromwich, for the night with its floor manager Dean Berrington - who has been accused of being the robbers "inside man" - when the raiders struck on April 9 last year.
Mr Kang confessed to the Wolverhampton Crown Court jury: "I was extremely frightened - anybody would have been.
"A black handgun was pointed at me and I was told not to move."
His hands were pinned behind his back and bound with silver gaffer tape which was then wrapped around his body.
His ankles were also secured with tape before he was pushed to the floor by the masked robbers and told not to look around.
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Berrington was also trussed up but this was a "pantomime" compared with the way the supervisor was handled, alleged Mr Stefan Kolodynski, prosecuting, who maintained: "There was a perfunctory attempt to tie him up."
Mr Kang continued: "They wanted access to the cigarette room and shouted at me. Dean Berrington had responsibility to lock it up and I had seen him putting the alarm on."
It was then deactivated by, or for, the gang who got into the building through a staff fire exit door, the jury heard.
It should have locked automatically when closed by Mr Kang after he spotted the raiders outside during a final round of security checks with the 41-year-old floor manager, the jury heard.
He explained: "I opened it, stepped outside and saw five masked men standing still. I told Dean and he told me to get back in. I shut the door behind me and was walking towards another door when they came in. They could not have done that unless someone had tampered with the lock."
The haul of cigarettes was loaded onto a Mitsubishi van belonging to Hyperama for which the raiders had an ignition key which should have been kept in the cash office.
Berrington called the police and activated the alarm after he and Mr Kang freed themselves after the raiders had taken half an hour collecting cigarettes and money from the safe, it was said.
The van had a tracker which allowed detectives to follow its route which ended outside the Jesson Road, Walsall home of 52-year-old local shop owner Satnam Singh whose garage was allegedly filled with the stolen cigarettes.
Members of the gang were taken to and from the warehouse in a VW belonging to Jay Brownhill, who voluntarily gave himself up to police on April 16 last year. He has since lost his life in a motorcycle accident.
Three other men have admitted being among those involved in the raid and will be sentenced after the current trial, the jury was told.
Brandon Morris, aged 22 from Lellow Street, West Bromwich - whose phone was found in the VW - Berrington of Crankhall Lane, Wednesbury and Singh deny conspiracy to rob and possession of an imitation firearm. The case continues.