Firefighters scrambled to Boots in Wolverhampton city centre today when smoke was reported to be pouring out of the building.
However, as crowds gathered in front of the Dudley Street store it became apparent that the smoke was not flowing from a fire but from a security mechanism inside the shop.
Fire crews from Fallings Park and Tettenhall forced their way into the shop and freed two people who had been trapped inside.
It is not yet known what triggered the 'smoke cloak' - a device designed to prevent intruders from getting away by filling a room with dense fog - but the pharmacy and cosmetics store was overflowing with light-grey smoke.
Firefighters were called 6.39pm and left once the device had been deactivated at 7.15pm.
Police officers were also on the scene.Subscribe to our Newsletter