The Wizard of Oz almost made an entire audience disappear when the Wicked Witch of the West disappeared in a puff of smoke – and set off a fire alarm.

The scare happened midway through the first schools’ performance of the packed-out panto at Swallows Leisure Centre, Sittingbourne.

As Dorothy (Rachael Rhodes) threw “water” over the witch, played by Victoria Roberts, the baddie disappeared behind a wall of red smoke.

Seconds later the fire alarm sounded throughout the sports complex.

As staff near the entrance began evacuating children from the Adventure Zone the panto cast in the sports hall – converted into a temporary theatre – battled on with the 10am performance on Thursday by singing Uptown Funk over the alarm.

Darren Paine, executive producer for Liverpool-based Trio Entertainment, said: “The smoke seeped into another sensor. In all the years we have been coming to Swallows this has never happened before.”

Andrea Chase, who organises the annual panto for the leisure centre, said: “Reception staff knew the alarm had been raised in the sports hall but as a precaution began evacuating children from the Adventure Zone.

“Sports hall staff realised the special effect had triggered the alarm and allowed the show to carry on. We apologise if anyone was concerned about the experience.”

The alarm was finally silenced and the source of the leak was isolated for future shows. The panto, which stars former Bill actor Chris Simmons as the Scarecrow and CBBC’s Lucinda Rhodes as the Good Fairy, runs until Christmas Eve.

More than 150 primary school children and their teachers were in the audience at the time.