All the dust-covered injured managed to walk away from the building, although some injuries were described as 'serious'.
The collapse occurred shortly after 8pm during a performance of The Curious Incident of the Dog in the Night-Time at the Apollo Theatre in Shaftesbury Avenue.
Fire crews were on the scene within three minutes after a large chunk of ceiling plaster came down onto the balcony.
The theatre, built in 1901, seats 755 people and is owned by Nimax Theatres.
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