Authorities are carrying out a structural assessment at the Apollo Theatre after the partial collapse of its ceiling injured more than 75 people in the packed auditorium.
An initial report is expected Friday after an overnight survey. The building remains cordoned off.
Eyewitnesses have described chaos and panic as large hunks of plaster and dust rained down on the audience 45 minutes into a performance of "The Curious Incident Of The Dog In The Night-Time."
Playwright Simon Stephens used Twitter to thank the public for messages of support. The play was adapted from Mark Haddon's successful novel.
The Edwardian theater is more than 100 years old. Nimax Theatres, which owns the Apollo, described the incident as "shocking and upsetting."
Police say seven of the injuries are serious.