An investigation has begun into how a ceiling at a theatre in London’s West End collapsed, injuring 76 people, seven of them seriously.<br /><br />The audience at the Apollo was watching a performance of The Curious Incident Of The Dog In The Night-Time, when around 10 square metres of heavy plasterwork and parts of balconies crashed down on top of them.<br /><br />Emergency services arrived within minutes and used a nearby theatre to treat some of the injured. Others were taken to hospital on three London buses.<br /><br />It’s thought that water may have dripped through cracks in the ceiling after heavy rainfall. The roof itself showed little sign of damage.<br /><br />The grade II listed building is more than a century old.<br /><br />Structural engineers are now investigating what caused the collapse. <br /><br />Westminster council says it will be carrying out safety checks on other historic theaters in the area.