Up to 15 people were hurt when a chandelier came loose and part of the ceiling fell down at a theatre in London's West End.
Police and ambulance staff were called to the theatre
Audience members ran for safety as plaster started to fall during When Harry Met Sally at the Theatre Royal Haymarket at 2205 BST on Saturday.
The show's star, Luke Perry, leapt off the stage to help people to safety, an eyewitness told BBC Radio Five Live.
Ambulances were called but there were thought to be no serious injuries.
The chandelier dropped about four feet from the ceiling but was stopped from plunging into the audience by its safety rope.
The motion dislodged parts of the ceiling, which fell into the auditorium, police said.
Eyewitness Carl Hamilton said the show was in its final stages when he felt bits of plaster falling from the ceiling before "pandemonium" broke out.
He said: "Maybe one or two square metres of plaster had fallen from the ceiling and I could see lots of wood... It was a very large chandelier and everyone was looking concerned that it might fall.
"I turned around and I saw Luke standing about three or four rows from the front.
"He was obviously quite concerned to get members of the audience out, as was the rest of the cast.
"I think he was very gallant and the rest of them conducted themselves brilliantly. It was a great performance and it's a shame it had to end this way."
The Health and Safety Executive has been informed.
A spokesman for the theatre said a statement would be released on Monday.