Five people were taken to hospital and several others were injured when a roof collapsed during a Piccadilly Theatre show in London’s West End.
The venue in Denman Street was packed for a performance of the Arthur Miller play Death of a Salesman, starring US actor Wendell Pierce.
Screaming was heard from the circle when part of the ceiling collapsed just before 20:00 GMT on Wednesday, covering many theatre-goers in plaster debris.
More than 1,000 people were evacuated.
Wendell Pierce, who plays Willy Loman in the show – which only opened on Monday – apologised for having to stop the show and evacuate the theatre.
A video shared on social media shows the US actor outside the venue asking the crowd to come back and see the play another time.
“We’re so honoured that you came tonight. We are so sorry that this happened,” he said.
BBC journalist Iain Haddow, who was in the audience, said the collapse happened about 20 minutes into the show.
He said that before the collapse there had been a steady drop of water “which turned progressively into a stream” – although it was not raining at the time – and said there was some panic when the ceiling fell in.
He said that outside the theatre there was scaffolding and building work going on.
Following the collapse, a spokeswoman for theatre production company Ambassador Theatre Group (ATG) confirmed the section of ceiling collapsed in the rear upper circleand that five people required hospital treatment.
“We take the safety and security of our audiences extremely seriously and we are doing everything we can to ascertain the cause of the incident,” she said.
The company said on its website it would be making an announcement later “regarding the recommencing of performances”.
In December 2013, 76 people were injured, seven seriously, when part of a ceiling at London’s Apollo Theatre collapsed during a show, while 1,200 people had to leave the Queen’s Theatre in Shaftesbury Avenue, following a small fire during a matinee performance of Les Miserables.