Updated

A packed London theater collapsed in the middle of a performance Thursday night, raining chunks of debris on playgoers and injuring more than 80, according to ambulance services.

At least seven of the injuries were described as serious. Police said they weren't aware of any fatalities "at this early stage."

Fire engines and police raced to the 775-seat Apollo Theatre on Shaftesbury Avenue in central London during the performance of “The Curious Incident of the Dog in the Night-Time.” Although first reports said the ceiling had collapsed, later accounts indicated it could have been a balcony or the roof.

Theatergoers reported people in the stalls had been hit by large chunks of falling debris.

Authorities said all those trapped had been freed, the Associated Press reported. Many of the injured were treated at a nearby theater.

Martin Bostock was in the audience with his family, and said "complete chaos" erupted in the theater.

"At first we thought it was part of the show," he told Sky News. "Then I got hit on the head."

Big chunks of mortar had fallen on people’s heads,” Simon Usborne, who witnessed the collapse, told Fox News.

Witnesses told British media that the theater in London's famous West End was packed during the holiday season to see the show, which is based on the best-selling novel by Mark Haddon.

"We thought it was part of the show, until something hit me on the head very hard," one man told the BBC, speaking from the foyer of the theater while he was being evaluated by emergency workers. "I thought we were all going to be in really, really serious trouble."

"Within an instant, the entire roof caved in," another witness told the BBC

The Associated Press contributed to this report