Authorities in London say more than 75 people were injured when part of the ceiling of a theater collapsed Thursday night. Seven of the injuries are serious.

Police and fire crews outside the Apollo Theatre in London after the collapse of a balcony during a performance (Mary Turner/Getty Images)

The collapse at London's Apollo Theatre happened during a Christmas holiday season performance. Police say plaster and masonry from a section of the ceiling tumbled down, bringing parts of the theater's balconies down with it onto the audience.

More than 700 people were in the theater at the time.

One person in the audience says she was seated near the stage and heard the main actor shout, "watch out!"

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