(BBC News) MORE than 80 people have been injured, four seriously, after part of a ceiling in London’s Apollo Theatre collapsed during a show, police say.

The venue in Shaftesbury Avenue was packed for a performance of The Curious Incident Of The Dog in the Night-Time.
Eyewitnesses heard “a crackling” noise before the collapse at about 20:15 GMT. Theatre-goers left covered in debris.
London Ambulance said there were 81 walking wounded and that all those who were trapped earlier had been freed.
Some 25 ambulance crews and an air ambulance attended the scene, it said.
London Fire Brigade said four people were seriously injured but none have life-threatening injuries.
It said its “search is now complete” and the theatre has been sealed off.
Eight fire engines and more than 50 firefighters attended the incident in London’s busy West End theatre district, along with hundreds of police officers.
The Apollo’s ornate plasterwork ceiling collapsed and brought part of the lighting rig down, it said.
In a media briefing the fire brigade said its officers inspected the theatre’s roof via an aerial ladder platform that had been raised above the building
It said it did not believe scaffolding on adjacent building had anything to do with the incident.
Nick Harding from Kingsland Fire Station said: “A section of the theatre’s ceiling collapsed onto the audience who were watching the show. The ceiling took parts of the balconies down with it.
“Firefighters worked really hard in very difficult conditions… They rescued people from the theatre, made the area safe and then helped ambulance crews with the injured.
“Specialist urban search and rescue crews were also called to the scene to make sure no one was trapped.”
He added: “In my time as a fire officer I’ve never seen an incident like this.”
Firefighters said the theatre had been almost full and 720 people were watching the performance.
The Met Police said more than 40 walking wounded were treated at the nearby Gielgud Theatre, while three London buses were used to transport others to hospitals.
Guy’s and St Thomas’ NHS Trust said 34 adults and five children were being treated at the accident and emergency department at St Thomas’ Hospital.
The majority had cuts and bruises, and a small number had fractures. The three most serious cases had injuries to the neck and back, or head.
The trust said at this stage there were no life-threatening injuries.
In a statement it said: “We have had a fantastic response from staff – both already on-site and those who came in from home – to help.”
Prime Minister David Cameron tweeted: “I’ve been updated regularly on the Apollo incident. I’m grateful for the fast work of the emergency services in helping the injured.”
A spokesman for London Mayor Boris Johnson said: “He has spoken to the Met Police Commissioner and is liaising with the relevant agencies. His thoughts and prayers are with those involved in what is clearly a very serious incident.”
Witnesses earlier said they had seen people leaving the building, covered in dust and plaster – with some people bleeding and crying.
‘Strange crackling noise’
Amy Lecoz, who was at the theatre with her two children, aged 16 and 19, said: “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 said she heard a “strange crackling noise” before “the roof just crumpled”.