The unarmed man claimed to be an innocent party who was being threatened by the one with the machete and he pleaded with the staff member to let him out. But those outside blocked the route by pulling the door tightly shut while holding a chair against the broken glass.

The suspects eventually managed to escape by climbing out through a bathroom window at the back of the property and are being sought by West Midlands Police.

Rajasingam Tharshiya, the owner of the Taas Express store, said one of the suspects managed to escape before the door was pulled shut, but the other two were trapped.

Describing his ordeal, he said: “These two lads came in with knives and started demanding money from my staff. He had the presence of mind to run from behind the counter and out of the door, one of them just beat him to the door and ran away.

“The other guy trapped inside started banging on the glass and the third man I believe was also with them, as they both escaped out of the bathroom window together.

“It’s almost like the man with the knife tries to take him as a fake hostage at one point to get my staff to try and open the door. Some other neighbours came to help pull the door shut – they were very brave, as he smashed up the windows.

“The police arrived while they were still inside, but were reluctant to go inside for some reason. At that point, they squeezed out of the bathroom window.

“It is very frightening this can happen, and our worker was very shaken up but luckily unharmed.”

A police spokesman said: “We were called just before 7pm on 18 April to reports of a disorder at a shop on Bearwood Road, Smethwick. A shop worker was threatened with a knife and offenders attempted to take items from the store.

“The shop worker, along with members of the public, attempted to lock the offenders in the store to prevent them from fleeing the scene. During this, the front door of the store was smashed.

“A boy, aged 17, was arrested on suspicion of robbery and has since been bailed pending further enquiries.”