"We advised that there were some concerns with some of the stands that they wanted to use, and alongside the carol singers this may cause a risk to fire escape procedures, " she said.

BBC: NEWS | UK | England | West Yorkshire | Carols ban 'a misunderstanding'

It is too early to say what the cause of the fire may be.

BBC: Fire on Rotherwas Industrial Estate

The NTSB, which is investigating the Boston incident, hasn't yet determined the root cause of the fire and may never be able to do so.

NPR: NTSB Probes Safety Testing Of Boeing 787 Batteries