UPDATE

Theatre-goers have been pulled from the rubble by emergency services workers after a part of the roof in the Apollo theatre in London’s West End collapsed during a performance, eyewitnesses say.

Police and the London Fire Brigade were called to the theatre in Shaftesbury Avenue shortly after 8.15pm on Thursday (7.15am AEDT Friday).

An official statement by the London Fire Brigade said a section of the theatre’s ceiling “collapsed onto the audience who were watching the show and the ceiling took parts of the balconies down with it”.

“Specialist urban search and rescue crews were also called to the scene to make sure no one was trapped. Fortunately all those who were trapped have been rescued and treated for injuries or taken to hospital,” the statement said.

It is thought that about 720 people were inside the theatre at the time of the collapse. There are no reports of deaths. The collapse occurred during a performance of The Curious Incident Of The Dog In The Night-time.

The London Ambulance Service said it had treated “88 patients, of whom 81 had suffered minor injuries and were walking wounded”.

“Seven patients with more serious injuries have also been treated and taken to hospital,” said a statement from the ambulance service.

Eyewitnesses said they saw people being escorted out of the building, covered in dust and debris.

Lobby filled with head injuries. pic.twitter.com/Q5Y9CDhuAG

— Simon Usborne (@susborne) December 19, 2013

Amy Lecoz, who was in the audience with her 16-year-old and 19-year-old, told the BBC that “the entire dome roof fell down on the audience just in front of us”.

“We were protected by the balcony above and we ran. People started screaming. We thought it was water… We thought it was a part of the show. I grabbed my kids and ran.”

Another witness told the BBC that she heard a “strange crackling noise” before “the roof just crumpled”.

The theatre “suddenly went dark” with “dust clouds everywhere”, she said.

“You could see everyone ran off the stage … it went dark”.

More soon